• Journal of Communications and Networks
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• 제5권4호
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• pp.309-318
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• 2003

This paper presents an in-depth study of a UWB indoor radio channel between 1 and 9 GHz, which was used for the subsequent development of a new statistical UWB multipath channel model, focusing on short range indoor scenarios. The channel sounding process was carried out covering different indoor environments, such as laboratories, halls or corridors. A combination of new and traditional parameters has been used to accurately model the channel impulse response in order to perform a precise temporal estimation of the received pulse shape. This model is designed specifically for UWB digital systems, where the received pulse is correlated with an estimated replica of itself. The precision of the model has been verified through the comparison with measured data from equivalent scenarios and cases, and highly satisfactory results were obtained.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 2003년도 추계학술대회
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• pp.41-54
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• 2003

This study examines group process patterns when Instant Messaging is used for decision-making, and examines how these patterns are associated with creative solutions to problems. Our research suggests that certain communication behavior of a group, when appropriately organized, can enhance creative production of outcomes. A qualitative analysis is conducted on communication patterns based on text-based conversation protocols. Specifically, this research tries to extend existing studies on group-work by focusing on the interactive communication process among participants. Study results include that the production of creative outcome depends on the temporal sequence of discussion pattern among group members. (1) Appropriate control of the discussion process is essential to obtain a high level of performance. (2) It is also important to set up discussion rules and rules for the use of communication medium in the early stages of the discussion . (3) Active participants use various protocol types while less-active members rely mainly on 'cognitive' protocols.

• 한국언어정보학회지:언어와정보
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• 제4권2호
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• pp.93-105
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• 2000

I argue in this paper that the sequence of tense (SOT) phenomenon can be accounted for without positing a SOT rule, focusing on the contrast between the past under-past sentences which lead to ambiguity and those sentences which do not. The different interpreta- tion of past under past sentences depends on whether the stative or then non-stative predicates occur in the complement clauses in the propositional attitude verbs. Based on this, I also argue that the embedded past tense does not contribute to the seman- tics past tense in the complement clause. Instead, it is due to the occurrence of the stative or non-stative predicates in the complement clauses. The stative predicates are associated with the temporal precedence or the overlap relation, whereas the non-stative predicates the precedence relation only. This fact triggers the contrast in past- under- past sentences.(Korea University)

• 디자인학연구
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• 제19권3호
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• pp.59-70
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• 2006

Narratologists have long raised the question of how narrative theories could be applied to other disciplines that involve stories and storytelling. Focusing on recently revitalized concepts of space, sequence, and story, this article attempts to illustrate narrative constructions in various fields of arts and humanities and examine them particularly in typographical works. Through the concept of narrativity, this article highlights the prevalent uses of narrative in typography and scrutinizes the ways in which a sense of storyness is forming and emerging in some typographical works. Particularly emphasized are the importance of and interplay between the formal and cultural attributes of narrative that transform the spatial world of visual images to the temporal world of stories. Narrative is arguably the most familiar, interesting, and effective medium of communication regardless of age, race, and culture, and can be critically rethought to apply to typography and design.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1374-1378
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• 2004

Railway conflict detection and resolution problem (RCDRP) involves complicated field constraints that should be considered for practical service. In this paper, we address those constraints in brief. Particularly, following situations are addressed; (1) temporal change of network topology, (2) consideration of diverse conditions of track and train, for example, single/double tracks and passenger/freight service, (3) siding capacity limitation, (4) bidirectional sides used by both inbound and outbound trains, (5) regulation for passenger transfer service, (6) consideration of siding length, (7) Restriction on stopping before the track segment with steep slope.

• Animal cells and systems
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• 제12권1호
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• pp.1-9
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• 2008

In the developing limb, chondrogenesis is an important prerequisite for the formation of cartilage whose template is required for bone formation. Chondrogenesis is a tightly regulated multi-step process, including mesenchymal cell recruitment/migration, prechondrogenic condensation of the mesenchymal cells, commitment to the chondrogenic lineage, and differentiation into chondrocytes. This process is controlled exquisitely by cellular interactions with the surrounding matrix and regulating factors that initiate or suppress cellular signaling pathways and transcription of specific genes in a temporal-spatial manner. Understanding the cellular and molecular mechanisms of chondrogenesis is important not only in the context of establishing basic principle of developmental biology but also in providing research direction toward preventive and/or regenerative medicine. Here, I will overview the current understanding of cellular and molecular mechanisms contributing to prechondrogenic condensation processes, the crucial steps for chondrogenesis, focusing on cell-cell and cell-matrix interactions.

• 비파괴검사학회지
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• 제28권1호
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• pp.54-58
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• 2008

Time reversal (TR) of body waves in fluids and isotropic solids has been used in many applications including ultrasonic NDE. However, the study of the TR method for anisotropic materials is not well established. In this paper, the full reconstruction of the input signal is investigated for anisotropic media using an analytical formulation, called a modular Gaussian beam (MGB) model. The time reversal operation of this model in the frequency domain is done by taking the complex conjugate of the Gaussian amplitude and phase received at the TR mirror position. A narrowband reference signal having a particular frequency and number of cycles is then multiplied and the whole signal is inverse Fourier transformed. The original input signal is seen to be fully restored by the TR process of MGB model and this model can be more generalized to simulate the spatial and temporal focusing effects due to TR process in anisotropic materials.

• 한국표면공학회지
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• 제50권1호
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• pp.1-9
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• 2017

Design of novel materials in renewable energy systems plays a key role in powering transportation vehicles and portable electronics. This review introduces the research work of first principles-based computational design for the materials over the last decade to accomplish the goal with less financial and temporal cost beyond the conventional approach, especially, focusing on electrocatalyst toward a proton exchange membrane fuel cell (PEMFC). It is proposed that the new method combined with experimental validation, can provide fundamental descriptors and mechanical understanding for optimal efficiency control of a whole system. Advancing these methods can even realize a computational platform of the materials genome, which can substantially reduce the time period from discovery to commercialization into markets of new materials.

• Journal of Information Processing Systems
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• 제15권1호
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• pp.169-180
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• 2019

Transmitting visual information over a broadcasting network is not only prone to a copyright violation but also is a forgery. Authenticating such information and protecting its authorship rights call for more advanced data encoding. To this end, electronic watermarking is often adopted to embed inscriptive signature in imaging data. Most existing watermarking methods while focusing on robustness against degradation remain lacking of measurement against security loophole in which the encrypting scheme once discovered may be recreated by an unauthorized party. This could reveal the underlying signature which may potentially be replaced or forged. This paper therefore proposes a novel digital watermarking scheme in temporal-frequency domain. Unlike other typical wavelet based watermarking, the proposed scheme employed the Lorenz chaotic map to specify embedding positions. Effectively making this is not only a formidable method to decrypt but also a stronger will against deterministic attacks. Simulation report herein highlights its strength to withstand spatial and frequent adulterations, e.g., lossy compression, filtering, zooming and noise.

• KDI Journal of Economic Policy
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• 제44권1호
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• pp.77-98
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• 2022

This paper empirically verifies that the types of capital adjustment costs serve as an important mechanism in relation to investment decision-making after confirming that the investment dispersion of Korean firms is pro-cyclical and can affect business cycles. Specifically, it is found through empirical methods using corporate financial data that capital adjustment costs generally assumed to take a quadratic form in macroeconomics are asymmetric and irreversible in the Korean economy. In particular, capital adjustment costs are empirically proven to cause investment dispersion to expand given that the substitution effect of the marginal value to the marginal cost for one unit of investment in the inter-temporal investment decision is affected by that cost with regard to the resale of owned equipment assets, as opposed to new investments in equipment assets. We ultimately show, albeit indirectly, that investment dispersion can affect business cycles as capital adjustment costs influences investment decisions. What is implied is that the capital adjustment cost is not merely an exogenously deep parameter that fits the dynamics of business cycles in a macroeconomic model but could instead be a policy variable that can be endogenized through government policies.