라이브 시뮬레이션과 예술적 전략 : 이안 쳉의 작품을 중심으로

윤소영 홍익대학교 대학원 2020 국내석사

This study explores the artistic possibilities of computer simulation, which proves that contemporary technology and art are intersecting. Thus, it sheds light on an American Artist, Ian Cheng(1984-). Cheng is a artist who works through photos and videos based on media. In particular, the work operates with computer simulation, which consists of algorithms. Recently Cheng presents a new technique called ‘Live Simulation’. He starts from simple programming to apply artificial intelligence to characters for the autonomous creations, and never-ending timeliness to the process of Live Simulation. This computer programmed work provides us with time to reconsider how we live in this era by showing the most similarly appearance of living, but artificial organics and society. Cheng is a contemporary artist with many curators and art galleries paying attention and have shown active activities even now. Still there is no exhibition has been held in Korea, so research on Cheng is lack. In addition, research on the artistic discussion of virtuality and virtual space is being done rapidly, and this kind of works that introduce simulation emergences frequently, but there is little research to establish artistic value about it. This thesis is based on the analysis of Ian Cheng and his works while attempts to identify the value of art that extends to simulation. This thesis starts a theoretical quest for the existence of analog and digital images, and further seeks the meaning of simulation and his artistic direction. Theoretical analysis is mainly dealt with in Chapter II. The existential analysis of the image reveals that it has broken away from the relationship of reproducibility dependent on the reality of the existing image, centering on Walter Benjamin's image theory and Jean Baudrillard's Simulacre. Subsequently, this thesis examines the technical methods of computer simulation, and notes the similarities between digital images and simulations for the aforementioned deformed reproducibility. It also analyzes the artistic significance of the new way of existence of digital images with the discussion of virtuality. And it explains <RMB City Project> the work of Cao Fei, a artist who uses computer simulations in the contemporary era to identify effective values. The technical collaboration shown by Ian Cheng in his works of art, especially the purpose of using computer simulations and five works based on it, is classified into three periods and analyzed closely in chapters III and IV. It aims to analyze the artistic orientation of around a decade of art works from 2009 to 2020, and to identify the artistic strategies that Live Simulation presents in the realm of contemporary art. At this point, this study do not focus solely on a single simulation technique or media characteristic, and it would like to understand widely from the philosophical discussion mentioned by the artist, the domain of cognitive science, and the discussion of games which art and technology cross over. The purpose of this study is to analyze the artistic value of Ian Cheng's Live Simulation, which is also meaningful in identifying how we can give the artistic meaning that arises in the realm of convergence of contemporary technology and art. 본 연구는 동시대 기술과 예술이 교차하고 있음을 증명하는 컴퓨터 시뮬레이션의 가지는 예술적 가능성을 탐구한다. 이에 미국 출신 작가 이안 쳉(Ian Cheng, 1984-)을 조명한다. 쳉은 미디어를 기반으로 사진, 영상을 통한 작품 활동을 하는 작가이다. 특히 알고리즘으로 이루어진 컴퓨터 시뮬레이션을 통해 작업을 전개하며 현재는 라이브 시뮬레이션이라는 새로운 기법을 통한 작품을 선보인다. 그는 라이브 시뮬레이션의 자율적 생성과정과 작품의 끝나지 않는 시간성을 위해 단순 프로그래밍에서 나아가 캐릭터에 인공지능을 탑재한다. 이렇게 생성된 작품은 살아있는 듯한 유기적인 인공 생산물의 모습과 사회의 모습을 보여줌으로써 우리가 어떤 모습으로 이 시대를 살아가고 있는지 재고해보는 시간을 선사한다. 다수의 큐레이터와 미술관들이 주목하는 동시대 작가이며 지금도 활발한 활동을 선보이지만 국내 전시는 이루어진 바 없기에, 쳉에 대한 연구 역시 미진하다. 또한 가상성과 가상공간의 예술적 논의에 대한 연구가 빠른 속도로 이루어지고 있으며, 시뮬레이션을 도입한 예술작품이 빈번하게 등장하고 있지만 그럼에도 이에 대한 예술성을 확립하는 연구는 거의 진행되지 않는다. 본 논문은 이안 쳉과 그의 작품에 대한 분석을 바탕으로 하며 동시에 시뮬레이션에 기대어 확장하는 예술의 가치를 확인하는 것을 시도한다. 본 논문에서는 이안 쳉의 작품을 분석하기에 앞서 아날로그와 디지털 이미지의 존재론에 대한 이론적인 탐색을 시작하며 나아가 시뮬레이션이 가지는 의미와 그의 예술적 방향성을 모색한다. 이론적 분석은 Ⅱ장에서 중점적으로 다뤄진다. 이미지의 존재론적 분석은 발터 벤야민(Walter Benjamin)의 이미지론과 장 보드리야르(Jean Baudrillard)의 시뮬라크르(Simulacre)를 중심으로 기존의 이미지가 가지던 실재에게 종속된 재현의 관계를 탈피했음을 밝힌다. 이후 컴퓨터 시뮬레이션의 기술적 방식을 이해하고, 앞서 언급한 탈피된 재현성에 대한 디지털 이미지와 시뮬레이션의 유사성에 주목한다. 또한 디지털 이미지의 새로운 존재 방식이 갖는 예술적 유의미함을 가상성의 논의와 함께 분석한다. 그리고 동시대에서 컴퓨터 시뮬레이션을 활용하는 작가 차오 페이(Cao Fei)의 작품 <RMB City Project>를 살펴봄으로써 실제적 유형을 이해한다. 이안 쳉이 그의 예술 작품에서 보여주는 기술적 협업, 특히 컴퓨터 시뮬레이션을 사용하는 목적과 이를 토대로 하는 작품들 다섯 개를 세 시기로 분류하여 Ⅲ장과 Ⅳ장에서 면밀히 분석한다. 2009년부터 현재인 2020년까지 진행되는 10여 년간의 작품과 쳉의 예술적 방향성을 분석하며, 라이브 시뮬레이션이 동시대 예술의 영역에서 선사하는 예술적 전략을 파악하는 것을 목표로 한다. 이러한 지점에서 단일의 시뮬레이션 기법 혹은 매체적 특성에만 초점을 맞추지 않았으며 작가가 언급한 철학적 논의와 인지과학의 영역, 그리고 예술과 기술이 교차하며 성장하는 게임에 대한 논의까지 폭 넓게 이해하고자 한다. 본 연구의 목적은 이안 쳉의 라이브 시뮬레이션이 함의하는 예술적 가치를 분석하는 것이며 이는 나아가 동시대 기술과 예술의 융·복합의 영역에서 발생하는 예술적 의미를 우리가 어떻게 부여할 수 있는지를 확인하는 데에 의의가 있다.

Anonymization and De-anonymization Attacks in Online Social Networks

Zhang, Cheng ProQuest Dissertations & Theses The George Washing 2020 해외박사(DDOD)

Online social networks have gained tremendous popularity recently. Millions of people use social network apps to share precious moments with friends and family. Users are often asked to provide personal information such as name, gender, address when using social networks. This information could be collected, analyzed, and re-published at large scale for both academic and business studies, and are usually processed by anonymization methods to protect user's privacy. However, these anonymized data could be misused by unauthorized third parties and even attackers to violate users' privacy. Several structure-based de-anonymization techniques have been proposed to re-identify the users in anonymized networks. In light of this, we first address the novel problems of re-identifying users in anonymized social networks with the help of public user attributes in this work. More specifically, we quantify the significance of attributes in a social network, based on which we propose an attribute-based similarity measure; then we design an algorithm by exploiting attribute-based similarity to de-anonymize social network data; finally we employ the dataset collected from a real-world online social network to evaluate our method. And experimental results show that public user attributes can significantly improve the de-anonymization accuracy.Extensive researches on anonymization techniques have been carried out to protect the data from privacy violations in social networks. Nevertheless, anonymization may affect the usability of the data as random noises are introduced, decreasing user experience. Therefore, a trade-off between privacy protection and data usability must be sought. In this work, we employ various graph and application utility metrics to investigate this trade-off. More specifically, we conduct an empirical study by implementing five state-of-the-art anonymization algorithms to analyze the graph and application utilities on a Facebook and a Twitter dataset. Our results indicate that most anonymization algorithms can partially or conditionally preserve the graph and application utilities and any single anonymization algorithm may not always perform well on different datasets.

Toward a Theory of Mandarin Quantification

Tsai, Cheng-Yu Harvard University 2015 해외박사(DDOD)

The goal of this dissertation is to show that certain puzzles in the syntax and semantics of Mandarin quantification can be explained from the perspective of Hamblin semantics. Following Kratzer and Shimoyama (2002), it is proposed that certain Mandarin quantificational expressions (including wh-phrases, numeral phrases, and strong quantificational phrases) denote sets of individual alternatives. They expand to sets of propositions in a pointwise manner and are selected by propositional operators. The distribution and interpretation of Mandarin quantificational expressions are constrained by the way alternatives interact with associated operators. Chapter 1 illustrates a number of issues in the behavior of Mandarin existential wh-phrases and numeral phrases, which cannot be easily explained by previous accounts. Chapter 2 investigates the properties of three logical operators haishi, huoshi and haiyoˇu, which provide the initial motivation for a Hamblin-style approach to the system of Mandarin quantification. It is argued that these three operators make a case for reading off Hamblin alternatives directly from the clausal syntax, and that, based on evidence from morphology and existential construal, wh-phrases in Mandarin pattern together with haishi-disjunctions and thus should receive a uniform semantic treatment. All types of quantificational expressions discussed in the first two chapters interact with the preverbal particle dou in one way or another, and thus this element plays a special role in Mandarin quantification. Chapter 3 critically reviews three influential theories on dou: Shyu's (1995) focus-based theory, Lin's (1996) distributivity-based theory, and Giannaki dou and Cheng's (2006) maximality-based theory. Chapter 4 is devoted to a novel proposal on the syntax and semantics of dou, where it is argued that syntactically dou is a modal head that agrees with a universal quantifier that collects alternatives introduced by the quantificational phrase to its left, and semantically provides existential quantification over possible worlds. It is shown that this proposal allows for a uniform account of dou across different dou-constructions, per the Hamblin-style analysis of quantificational phrases across-the-board. Finally, Chapter 5 reexamines the interpretations of existential wh-phrases and argues that in the few cases discussed the existential reading comes from not the c-commanding operator in the surface structure but from an invisible operator that collects alternatives. This operator is introduced into the syntax via agreement with the preverbal particle jiu, which is a related element to dou and is overt in some of the cases at hand but not in others. Further consequences of the present approach to the behavior of NumPs and strong quantifier phrases are also discussed.

Design and fabrication of long-wavelength vertical-cavity surface-emitting lasers using wafer bonding technologies

Lin, Hung-Cheng University of Illinois at Urbana-Champaign 2002 해외박사(DDOD)

Long-wavelength vertical-cavity surface-emitting lasers (VCSELs) emitting at 1.55 μm from GaInAsP/InP heterostructures are important optical sources for high-speed fiber-optic commutations. However, their development has been obstructed by the material disadvantages associated with the GaInAsP/InP distributed Bragg reflector (DBR) and the fabrication complexity of direct wafer bonding. In this work, a novel VCSEL fabrication method facilitated with new wafer bonding techniques has been developed to overcome these limitations. This process scheme provides more options on the DBR and substrate materials for long-wavelength VCSELs. In addition, the new wafer bonding techniques are less stringent on process requirements than the previous arts. Thus, the GaInAsP/InP VCSELs can be easily fabricated on lattice-mismatched substrates with high-contrast composite DBRs for a better performance, and therefore the need to grow thick epitaxial DBRs is eliminated. During the process development, substrate-independent DBRs such as polycrystalline-GaAs/Al-oxide, amorphous Si/Al-oxide, Si/Mg-oxide, and (Ga,As)/(Al,As) were investigated. New wafer bonding techniques using either spin-on glass or AuGeNiCr metal alloys as the bonding medium were developed. Using these wafer bonding techniques, the bonding interface can be formed outside the VCSEL cavity at low temperatures, reducing the mechanical and thermal impacts to the active region. In addition, processes for device formation such as ohmic contacts and chemical etching were studied and integrated. The results lead to the use of Si/Al-oxide DBRs and the metallic wafer bonding for the VCSEL fabrication. The Si/Al-oxide DBR provides a reflectance above 99.5% in six periods with a low thermal resistance and a broad stop bandwidth. The metallic wafer bonding offers a robust bonding interface, excellent thermal stability and optical reflectance. It also has a large process latitude and integration capability. Using the metallic bonding process, we successfully demonstrated 1.55 μm GaInAsP/lnP VCSELs on Si substrates. The fabricated VCSELs lase at 1.545 μm under pulsed operation at room temperature. The threshold current density is 1.2 kA/cm<super>2</super> and the output power is 5 μW from a 30 μm × 30 μm device, which is limited by the heating of the resistive p-contact materials and the resulting offset of material gain. This process is useful to long-wavelength VCSELs and other applications.

Essays on weak identification and cointegrating rank selection

Cheng, Xu Yale University 2010 해외박사(DDOD)

The first two chapters of my dissertation analyze estimation and inference with weak identification. The first chapter studies the least squares (LS) estimator of a nonlinear regression model. This chapter develops a local limit theory that provides a uniform approximation to the finite-sample distribution irrespective of the strength of identification, shows that standard confidence intervals (CIs) and subsampling CIs are prone to size distortion, and develops a new confidence interval (CI) that has good finite-sample coverage probability. This chapter also develops a sequential procedure to deal with multiple nonlinear regressors with different identification strength. It is shown that weak identification on any nonlinear regressor will lead to poor finite-sample approximation by standard asymptotic theory on all parameters in the model. The second chapter (joint with Donald W. K. Andrews) studies estimation and inference in a class of models in which the parameters are unidentified or weakly identified in some parts of the parameter space. It also introduces a method to make the tests and CS's robust to such identification problems. The results apply to a class of extremum estimators and corresponding tests and CS's, including maximum likelihood (ML), least squares (LS), quantile, generalized method of moments (GMM), generalized empirical likelihood (GEL), and minimum distance (MD) estimators. The consistency/lack-of-consistency and asymptotic distributions of the estimators are established under a full range of drifting sequences of true distributions. The asymptotic size (in a uniform sense) of standard tests and CS's is established. The third chapter studies long-run exchange rate dynamics by applying a semi-parametric cointegrating rank selection method introduced in Cheng and Phillips (2009a, 2009b). Cheng and Phillips (2009a, 2009b) show that a general semi-parametric error correction model (ECM) with one lag, information criteria based on the reduced rank regression (RRR) can consistently select the cointegrating rank provided that the penalty term goes to infinity at a rate slower than the sample size. This method is robust to persistent volatility shifts of an unknown form, which makes it particularly suitable for the long-run exchange rate dynamics. This empirical study assesses the information criteria-based approach and evaluates long-run exchange rate dynamics among seven major currencies under the flexible exchange rate regimes.

Using EMTP to analyze lightning surge and switching surge overvoltage : including the EMTP model selection

Cheng, Steve VDM Verlag Dr. Müller 2010 해외석사

Materials optimization and ghz spin dynamics of metallic ferromagnetic thin film heterostructures

Cheng, Cheng Columbia University 2014 해외박사(DDOD)

Metallic ferromagnetic (FM) thin film heterostructures play an important role in emerging magnetoelectronic devices, which introduce the spin degree of freedom of electrons into conventional charge-based electronic devices. As the majority of magnetoelectronic devices operate in the GHz frequency range, it is critical to understand the high-frequency magnetization dynamics in these structures. In this thesis, we start with the static magnetic properties of FM thin films and their optimization via the field-sputtering process incorporating a specially designed in-situ electromagnet. We focus on the origins of anisotropy and hysteresis/coercivity in soft magnetic thin films, which are most relevant to magentic susceptibility and power dissipation in applications in the sub-GHz frequency regime, such as magnetic-core integrated inductors. Next we explore GHz magnetization dynamics in thin-film heterostructures, both in semi-infinite samples and confined geometries. All investigations are rooted in the Landau-Lifshitz-Gilbert (LLG) equation, the equation of motion for magnetization. The phenomenological Gilbert damping parameter in the LLG equation has been interpreted, since the 1970's, in terms of the electrical resistivity. We present the first interpretation of the size effect in Gilbert damping in single metallic FM films based on this electron theory of damping. The LLG equation is intrinsically nonlinear, which provides possibilities for rf signal processing. We analyze the frequency doubling effect at small-angle magnetization precession from the first-order expansion of the LLG equation, and demonstrate second harmonic generation from Ni81 Fe19 (Permalloy) thin film under ferromagnetic resonance (FMR), three orders of magnitude more efficient than in ferrites traditionally used in rf devices. Though the efficiency is less than in semiconductor devices, we provide field- and frequency-selectivity in the second harmonic generation. To address further the relationship between the rf excitation and the magnetization dynamics in systems with higher complexity, such as multilayered thin films consisting of nonmagnetic (NM) and FM layers, we employ the powerful time-resolved x-ray magnetic circular dichroism (TR-XMCD) spectroscopy. Soft x-rays have element-specific absorption, leading to layer-specific magnetization detection provided the FM layers have distinctive compositions. We discovered that in contrast to what has been routinely assumed, for layer thicknesses well below the skin depth of the EM wave, a significant phase difference exists between the rf magnetic fields H rf in different FM layers separated by a Cu spacer layer. We propose an analysis based on the distribution of the EM waves in the film stack and substrate to interpret this striking observation. For confined geometries with lateral dimensions in the sub-micron regime, there has been a critical absence of experimental techniques which can image small-amplitude dynamics of these structures. We extend the TR-XMCD technique to scanning transmission x-ray microscopy (STXM), to observe directly the local magnetization dynamics in nanoscale FM thin-film elements, demonstrated at picosecond temporal, 40 nm spatial and < 6° angular resolution. The experimental data are compared with our micromagnetic simulations based on the finite element analysis of the time-dependent LLG equation. We resolve standing spin wave modes in nanoscale Ni81 Fe19 thin film ellipses (1000 nm x 500 nm x 20 nm) with clear phase information to distinguish between degenerate eigenmodes with different symmetries for the first time. With the element-specific imaging capability of soft x-rays, spatial resolution up to 15 nm with improved optics, we see great potential for this technique to investigate functional devices with multiple FM layers, and provide insight into the studies of spin injection, manipulation and detection.

Labor Market Rigidities and Ramifications of the Asian Financial Crisis: What Can We Learn from Hong Kong's Experience?

Cheng, Chak Hung Jack The University of North Carolina at Chapel Hill 2011 해외박사(DDOD)

The economic downfall experienced by Hong Kong during the Asian financial crisis is bewildering since Hong Kong did not undergo large currency devaluations as did other affected Asian economies. The purpose of this dissertation is to ascertain whether the large impact of the Asian crisis on the Hong Kong economy can be attributed to labor market frictions. In the first part of this dissertation, I develop and estimate a dynamic stochastic general equilibrium model with sticky wages based on the work by Cheng and Salemi (2010). The chief findings of this analysis are that nominal wages in Hong Kong are very sticky and the significant rise in unemployment after the crisis can be predominantly ascribed to wage setting frictions. However, wage rigidities are not responsible for the large decline in output. The rationale behind this result is that labor compensations account for a rather small share of total production costs in Hong Kong. Hence, changes in wage costs have only a limited effect on prices and output. In the second part of this work, I estimate a standard search-matching model. I find that a standard search model cannot explain the data as well as the sticky wage model. In particular, volatility of wages implied by the search model is much higher than that in the data. Finally, in the last portion of this work, I add wage stickiness to the standard search model to further determine the role of wage rigidity in explaining the Hong Kong data. I find that incorporating wage rigidity into the search model can improve the model's ability to explain the volatility of nominal wages. Also, by conducting counterfactual experiments on the sticky wage search model, I confirm that wage rigidity significantly amplifed the impact of the Asian financial crisis on the Hong Kong economy.

The Influence of Chinese Localized Norm (Guanxi) on Group Risky Decision Making under Uncertainty

CHENG CHENG 아주대학교 2014 국내석사

We compared Guanxi groups with non-Guanxi groups in order to investigate the different attitudes of Chinese regarding risk, when close Guanxi (i.e., interpersonal relationship of Chinese) exists among group members and when Guanxi absents. 185 students from a Chinese university participated in our experiment. Our results revealed that Guanxi groups showed more favorable risk attitudes after group discussions than when they make risk choices individually, compared with non-Guanxi groups. This is attributed to the influence of Guanxi, traditional Chinese cultural terms, which emphasizes on the trust among group members and thus shift the risk decisions among group members. This study also provides a discussion of the implications of these results in terms of local culture influence on decisions regarding risk.

Studies on the Screening and Identification of Antimicrobial Actinomycetes and their Natural Products

Cheng, Jinhua Graduate School, Myongji University 2011 국내박사

Studies on the Screening and Identification of Antimicrobial Actinomycetes and their Natural Products Jinhua Cheng Department of the Environmental Engineering and Biotechnology Graduate School, Myongji University Advisor Joo-Won Suh A crisis is developing in the treatment of infectious diseases. Resistant microorganisms to currently prescribed antibiotics are increasing at a steady rate, and fewer and fewer antimicrobial agents are available to treat these infections. Organisms displaying a multiple drug resistance phenotype are becoming common in both nosocomial and community-acquired infections. This situation has stimulated the research in the continuous discovery of new drugs. Traditional method for identifying antibiotics by screening extracts from actinomycetes and fungi against pathogens is called ?whole-cell antibacterial screening?. Most antibiotics in clinical use are isolated by using this method. However, use of this method in the discovery of new drug is declining because of the low opportunity of finding a novel compounds. But this method guarantee the activity which is the most important factor in the development of a new drug, reuse of this method is estimated. Another trend in the screening method is the ?target-based screening?, using the bacterial genomics, combinatorial chemistry and high?throughput screening. This method is more specific and provides more possibility in discovering new compounds. In this study, I used both of the two methods to search for novel anti-MRSA and anti-fungal antibiotics which pose a great threat to human life and agricultural crops. In our extract library from rare actinomycetes, I selected strain MJM2077, MJM 2582 for anti-MRSA activity and MJM 1968 for antifungal activity. Isolation and purification of the active compounds from these strains were performed by several steps including organic chemical extraction, adsorption chromatography, size-exclude chromatography, and high pressure liquid chromatography. The structures of the purified compounds were analyzed by Nuclear Magnetic Resonance (NMR) and Mass. Anti-MRSA compound from MJM2077 was determined as echinomycin, which is known as anticancer compounds. In our result, this compound showed strong anti-MRSA activity and stability in strong acidic conditions, which give possibility for the development of oral anti-MRSA agent to institute vancomycin. Strain MJM2582 showed positive induction in the target-based screening for specific detection of glycopeptides antibiotics. This strain was identified as a new strain belongs to Amycolatopsis species according to the morphology, physiology and phylogenetic analysis. Active compound is strong hydrophilic and unstable in alkali conditions. Partially purified compounds showed molecular weight less than 1000, which is different with existing glycopeptides antibiotics. Antifungal compound from MJM1968 was determined as azalomycin F complex. In our study, MJM1968 and this compound showed strong activity in suppression of soil-borne fungi both in vitro and in vivo. According to the antagonistic test, MJM1968 showed strong inhibitory activity to Fusarium spp., Rhizoctonia spp., and Colletotrichum spp. Treatment of agricultural soil with MJM1968 reduced the native fungal population by more than 60% after 14days. Treatment of soil with 10000ppm crude extract lowered native fungal density by more than 80% after 14 days. These data demonstrate the broad-spectrum suppression of fungal pathogen in agricultural soil by MJM1968 and the active compound azalomycin F complex. Our result showed the possibility of development of biocontrol agent for suppression of soil-borne fungi. In conclusion, I isolated MJM2077 and MJM2582 for their strong anti-MRSA activity and MJM1968 for its strong antifungal activity by using whole-cell antibacterial screening and target-based screening method. The active compounds from them were isolated and the structures were analyzed, and the possibility of using them as clinical use antibiotics and biocontrol agent were elucidated.