• Journal of Information Processing Systems
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• 제14권4호
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• pp.877-891
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• 2018

In this paper, we propose a novel algorithm for rendering motion-blurred shadows utilizing a depth-time ranges shadow map. First, we render a scene from a light source to generate a shadow map. For each pixel in the shadow map, we store a list of depth-time ranges. Each range has two points defining a period where a particular geometry was visible to the light source and two distances from the light. Next, we render the scene from the camera to perform shadow tests. With the depths and times of each range, we can easily sample the shadow map at a particular receiver and time. Our algorithm runs entirely on GPUs and solves various problems encountered by previous approaches.

• 한국컴퓨터정보학회논문지
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• 제20권1호
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• pp.85-92
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• 2015

컴퓨터 게임 배경이 정교하게 표현되면서 그리드 기반으로 표현된 게임 맵에서 $A^*$ 알고리즘을 이용한 경로 찾기는 전체 게임 성능을 저해하는 요인이 되고 있다. 셀 단위의 세밀한 표현으로 상태 공간이 커져 탐색 시간이 증가하기 때문이다. 본 논문에서는 정규 그리드로 표현된 컴퓨터 게임 배경을 꼭지점 리스트로 된 다각형 기반 맵으로 변환하고 다각형의 꼭지점에 대한 가시성 정보를 이용하여 효율적인 경로 찾기가 가능하게 하는 방법을 제안한다. 다각형 기반 맵으로의 변환은 오프라인으로 전처리하여 실시간 쿼리에는 영향을 미치지 않도록 하며 꼭지점의 가시성 정보를 이용하는 휴리스틱을 설계함으로서 추정의 정확도를 높여 경로 탐색 시에 방문하는 노드수를 획기적으로 감소시키도록 한다. 시뮬레이션에서는 제안한 방법들이 그리드 기반 방식의 장점을 유지하면서 탐색 공간과 탐색 시간을 효율적으로 감소시킴을 확인한다.

• 수산해양교육연구
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• 제29권2호
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• pp.380-385
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• 2017

Maritime accidents caused by a ship include collisions, sinking, stranding and fire etc. This study is intending to consider fire accidents among such diverse marine accidents. It is much likely that various sorts of fires break out because crews are living in a narrow space for long periods of time consequent on the ship's characteristic of sailing on the sea. This study carried out a simulation through the special program for fire analysis - FDS (Fire Dynamics Simulator) in order to find the effective evacuation time, i.e. life survival time. Particularly, this study did comparative analysis of the influence on the survival of cadets based on the collected simulation data by fire size and sort. As a result of the analysis, It was analyzed the Evacuation Allowable Limit Temperature $60^{\circ}C$ and resulted that there is no influence in evacuation by temperature. In case of visibility analysis, it reached to 5m which is the Evacuation Allowable Limit at 117 seconds under the condition of wood fire in 1MW. When there is Kerosene in 1MW, it took 92.4 seconds to reach by 5m which is the Evacuation Allowable Limit. Theoretical evacuation time for the non-tilted ship was 118.8 seconds in 1MW sized fire so it is shown that the most passengers are met the evacuation safety in case of wood fire. However, the majority of passengers could not be ensured the evacuation safety in Kerosene case.

• 한국실내디자인학회논문집
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• 제25권5호
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• pp.157-166
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• 2016

This study is intended to examine the various kinds of emptiness that are shown in the empty spaces created by Hyo-Sang Seung and Louis I. Kahn. Architecture creates the usefulness of a certain space thanks to its emptiness. The word, 'Emptiness' has the following meanings, 'non-fulfillment', 'non-existence', 'emptiness', 'blankness', 'non-visibility' and 'non-limitation', etc. Such concepts of emptiness can be broadly divided into 'ideological emptiness', 'aesthetic' and 'architectural spatial'. Comparisons regarding such concepts of emptiness as they are expressed in the architectural spaces created by Hyo-sang Seung and Louis I. Kahn shall be identified in this study. Hyo-sang Seung tried to leave numerous open possibilities which can contain everything into a certain space since 'emptiness' is not being used at this moment. Louis I. Kahn tried to contain into a space the essence and silence of that space before something that exists is created. The 'emptiness' created by Hyo-sang Seung and Louis I. Kahn is a specific space which can contain more kinds of non-visible spaces than some visible ones. Thus, such spaces may contain various potentials which are possible because they are empty, because of changes in nature and time, and because of silence and intentions going beyond an artist's original intent.

• 천문학논총
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• 제30권2호
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• pp.629-631
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• 2015

In this proceedings, preliminary results of the KVN Source-Frequency Phase-Referencing (SFPR) observation of 3C 66A and 3C 66B are presented. The motivation of this work is to measure the core-shift of these 2 sources and study the temporal evolution of the jet opacity. Two more sources were observed as secondary reference calibrators and each source was observed at 22, 43, and 86 GHz simultaneously. Our preliminary results show that after using the observations at the lower frequency to calibrate those at the higher frequency of the same source, the residual visibility phases for each source at the higher frequencies became more aligned, and the coherence time became much longer; also, the residual phases for different sources, within 10 degrees angular separations, follow similar trends. After reference to the nearby calibrator, the SFPRed maps were obtained as well as the astrometric measurements, i.e. the combined coreshift. The measurements were found to be affected by structural blending effects because of the large beamsize of KVN, but this can be corrected with higher resolution maps (e.g. KAVA maps).

• 천문학회보
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• 제41권1호
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• pp.55.2-56
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• 2016

The spin states of asteroids is regarded as an important clue to understand not only the physical property of an individual object but also the dynamical evolution of the of the population as a whole. Single asteroids can be broadly classified into two separate groups according to their rotational states; Principal Axis (PA) and Non-Principal Axis (NPA) rotators. To date, lightcurve observations have been carried out mostly for PA asteroids. However, discovery of NPA objects has recently been increased due to new observing techniques, and this is the reason why rotational properties of NPA rotators became an issue. As a DEEP-South pilot study for NPA, we selected two targets, 5247 Krolv (1982 UP6) and 14764 Kilauea (7072 P-L) considering their Principal Axis Rotation (PAR) code and visibility. Observations were made between Jan. and Feb. 2016 for 17 nights employing Korea Microlensing Telescope Network (KMTNet) 1.6 m telescopes installed at SSO and SAAO using DEEP-South TO (Target of Opportunity) mode. To obtain lightcurves, we conducted time-series photometry using Johnson-Cousins R-filter. Multi-band photometry was also made with BVRI filters at the same time, for taxonomy. Their preliminary lightcurves and approximate mineralogy will be presented.

• 한국IT서비스학회지
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• 제22권2호
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• pp.41-56
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• 2023

Metaverse is a three-dimensional virtual space where virtual and reality interact and co-evolutionize, and social, cultural, and economic activities are carried out in it to create value. Among the types of metaverse, the virtual world metaverse is expected to bring innovation beyond time and space in all areas of industry and society following the Internet. This study empirically analyzed factors affecting consumer's intention to use the virtual world metaverse by an innovation diffusion perspective. It was analyzed as an expanded technology acceptance model by setting relative advantages, ease of use, and visibility among the attributes of the innovation diffusion, and social presence, telepresence, and interactivity among the characteristics of the virtual worlds as factors. The proposed research model and hypothesis were verified through a PLS structural equation analysis based on a survey of 216 people. Studies have shown that relative advantage, telepresence, and interactivity have a significant effect on perceived usefulness and perceived enjoyment, but visibility does not have a significant effect on perceived usefulness and perceived enjoyment. It was found that ease of use had a positive effect on perceived enjoyment, social presence had a positive effect on perceived usefulness, and perceived usefulness and perceived enjoyment had a positive effect on the intention to use, respectively. This study is meaningful in that it empirically analyzed the factors affecting the intention to use the virtual world metaverse by dividing the psychological characteristics that induce consumer behavior into perceived usefulness which is an extrinsic motivation and perceived enjoyment which is an intrinsic motivation.

• 한국재난정보학회 논문집
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• 제12권3호
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• pp.210-218
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• 2016

본 연구에서는 화재 해석 프로그램인 FDS와 Pathfinder를 이용하여 협소 거주공간의 사고재현을 위해 테스트베드의 화재를 시뮬레이션하였다. 해석 결과, 내부 구조 형태가 H형태인 경우가 피난대피 시간이 285초로 가장 빠르게 나타났다. 또한 실험 조건 중 출입구가 닫히고 스프링클러가 작동하는 경우가 온도의 분포가 가장 낮게 나타났으며, 이는 가시도와 연기농도에도 큰 영향을 끼치는 것으로 나타났다.

• 건축역사연구
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• 제32권5호
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• pp.95-105
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• 2023

Focusing on Hwaseokjeong in Paju, the work seeks to clarify the social production of Nujeong (樓亭: Korean traditional pavilions) space, which took place over the 1960s and 70s, and its cultural-political implications. To make the effort as such meaningful, a theoretical framework based not merely on the thesis of 'social production of space' advocated by Henri Lefebvre but especially on some discussions related to 'state production of space' is prepared, according to which Hwaseokjeong is analyzed and explained. As a consequence, two principal arguments are put forward: one is that Hwaseokjeong was a social space which had been built and constructed in accordance with the unique mode of production dominating Korean society at that time called 'the state mode of production (le mode de production étatique)'; the other is that what lies beneath the denotation of a 'social space of tradition restoration' that Hwaseokjeong appears to carry is in fact the connotation of 'infiltration of anti-communist ideology'. All of these claims are once again supported both by examining Roland Barthes's semiology and mythologies and by considering Hwaseokjeong's P yeonaek (扁額: a plaque or framed text) as 'the practice of naming power through Jesa (題詞: inscribing dedications)'. While providing a succinct summary, the paper finally evaluates what 'social production of space' implies to social practices of architecture and related criticisms by taking into account the relationship between visibility and readability of space including buildings.

• Advances in aircraft and spacecraft science
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• 제9권5호
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• pp.449-462
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• 2022

Space-telescopes placed in the Sun-Earth second Lagrange point (L2) observe the sky following a scan strategy that is usually based on a spin-precession motion. Knowing which regions of the sky will be more observed by the instrument is important for the science operations and the instrument calibration. Computing sky observation parameters numerically (discretizing time and the sky) can consume large amounts of time and computational resources, especially when high resolution isrequired.This problem becomesmore critical if quantities are evaluated at detector level instead of considering the instrument entire Field of View (FoV). In previous studies, the authors have derived analytic solutions for quantities that characterize the observation of each point in the sky in terms of observation time according to the scan strategy parameters and the instrument FoV. Analytic solutions allow to obtain results faster than using numerical methods as well as capture detailed characteristics which can be overseen due to discretization limitations. The original approach is based on the analytic expression of the instrument trace over the sky. Such equations are implicit and thusrequiresthe use of numeric solversto compute the quantities.In this work, a new and simpler approach for computing one ofsuch quantities(mean observation time) is presented.The quantity is first computed for pure spin motion and then the effect of the spin axis precession is incorporated under the assumption that the precession motion is slow compared to the spin motion.In this sense, this new approach further simplifies the analytic approach, sparing the use of numeric solvers, which reduces the complexity of the implementation and the computing time.