• 천문학회지
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• 제48권4호
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• pp.213-228
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• 2015

The Horizon Run 4 is a cosmological N-body simulation designed for the study of coupled evolution between galaxies and large-scale structures of the Universe, and for the test of galaxy formation models. Using 6300³ gravitating particles in a cubic box of L_box = 3150 h⁻¹Mpc, we build a dense forest of halo merger trees to trace the halo merger history with a halo mass resolution scale down to M_s = 2.7 × 10¹¹h⁻¹M_⊙. We build a set of particle and halo data, which can serve as testbeds for comparison of cosmological models and gravitational theories with observations. We find that the FoF halo mass function shows a substantial deviation from the universal form with tangible redshift evolution of amplitude and shape. At higher redshifts, the amplitude of the mass function is lower, and the functional form is shifted toward larger values of ln(1/σ). We also find that the baryonic acoustic oscillation feature in the two-point correlation function of mock galaxies becomes broader with a peak position moving to smaller scales and the peak amplitude decreasing for increasing directional cosine μ compared to the linear predictions. From the halo merger trees built from halo data at 75 redshifts, we measure the half-mass epoch of halos and find that less massive halos tend to reach half of their current mass at higher redshifts. Simulation outputs including snapshot data, past lightcone space data, and halo merger data are available at http://sdss.kias.re.kr/astro/Horizon-Run4.

• 한국실내디자인학회논문집
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• 제20권4호
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• pp.191-200
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• 2011

Street furniture such as benches, streetlamps, and shades which are easily accessible in cities has contributed to the promotion of active, lively environment for people living in cities. Furthermore, they make the characteristics of specific regions and cities, and are valued as a communication interface to restore the relationships between people and cities. The street furniture design with inherent publicness is an essential element for leisurely life and refined image of modern people who have experienced severance and mental poverty in uniform, vertical modern city space with the development of advanced science and technology. The purpose of this study is to analyze the new design approaches to street furniture which plays an important role in the determination of the images of modern city environment and to examine the characteristics and trends of such designs. First, in accordance with the flow of studies from publicness and public space to street furniture, the concept and meaning of publicness which is the basic element of public space were identified through theoretical examination, and the characteristics and roles of modern public space were analyzed through literature review, data review, and international cases. Based on the results of this theoretical analysis, the concept and meaning elements, function elements, and design elements of the street furniture which was planned in accordance with the goal and functions of public space were identified. For the meaning elements of street furniture design, fun, health, culture, sustainability, and vitalization were identified. For the function elements of street furniture design, convenience, safety, and delivery were identified. As the characteristics of modern street furniture design, convergent, green, digilog, functional, and universal designs were analyzed. This study is meaningful in that it recognized the roles of street furniture in modern public space as a concrete, practical environmental design element and estimated the development directions of street furniture design in public space.

• Journal of Communications and Networks
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• 제18권1호
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• pp.65-74
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• 2016

Ship ad-hoc network (SANET) extends the coverage of the maritime communication among ships with the reduced cost. To fulfill the growing demands of real-time services, the SANET requires an efficient clock time synchronization algorithm which has not been carefully investigated under the ad-hoc maritime environment. This is mainly because the conventional algorithms only suggest to decrease the beacon collision probability that diminishes the clock drift among the units. However, the SANET is a very large-scale network in terms of geographic scope, e.g., with 100 km coverage. The key factor to affect the synchronization performance is the signal propagation delay, which has not being carefully considered in the existing algorithms. Therefore, it requires a robust multi-hop synchronization algorithm to support the communication among hundreds of the ships under the maritime environment. The proposed algorithm has to face and overcome several challenges, i.e., physical clock, e.g., coordinated universal time (UTC)/global positioning system (GPS) unavailable due to the atrocious weather, network link stability, and large propagation delay in the SANET. In this paper, we propose a logical clock synchronization algorithm with multi-hop function for the SANET, namely multi-hop clock synchronization for SANET (MCSS). It works in an ad-hoc manner in case of no UTC/GPS being available, and the multi-hop function makes sure the link stability of the network. For the proposed MCSS, the synchronization time reference nodes (STRNs) are efficiently selected by considering the propagation delay, and the beacon collision can be decreased by the combination of adaptive timing synchronization procedure (ATSP) with the proposed STRN selection procedure. Based on the simulation results, we finalize the multi-hop frame structure of the SANET by considering the clock synchronization, where the physical layer parameters are contrived to meet the requirements of target applications.

• Geomechanics and Engineering
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• 제30권6호
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• pp.503-515
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• 2022

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyze the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control example, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD is in accordance with exponential function, and the relationship between structure surface frequency and permeability is also in accordance with exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to judge the permeability and safety of the rock mass by using the mechanical parameters of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

• Journal of Korean Neurosurgical Society
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• 제66권4호
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• pp.382-392
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• 2023

Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

• 한국방재학회 논문집
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• 제10권4호
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• pp.95-104
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• 2010

저류함수법은 한국의 홍수예경보시스템에서 가장 널리 사용되고 있는 강우-유출 모형 중 하나이다. 본 연구에서는 저류함수법의 매개변수를 운동파모형과 비교하여 물리적 의미를 고찰하고 국내 하천유역에서의 일반적인 적용방법을 도모하고자 한다. 두 모형의 기본적인 방정식을 이론적으로 비교한 결과 저류함수법에서 저류량과 비선형관계인 유출량의 멱승을 나타내는 P와 운동파모형에서 유출수심과 비선형관계를 보이는 단위폭당 유량의 멱승을 나타내는 p가 동일하다고 볼 수 있었다. 또한, 저류함수법에서 저류상수와 지체시간을 나타내는 K와 $T_l$은 운동파모형에서 유역특성상수를 나타내는 k, 유역면적 그리고 Hack의 법칙의 계수를 이용하여 관계식을 제시할 수 있었다. 이와 함께 한국에서의 저류함수법의 일반적인 적용을 위해 K와 $T_l$에 관한 매개변수 추정을 위한 식을 제안할 수 있었다. 이러한 관계식은 국내 전국에 산재한 17개의 댐지점에서의 101개의 호우사상으로부터 얻어졌다. 이들 관계식은 운동파 모형의 매개변수와 국내 하천유역에 대해 새롭게 발전된 형태로 얻어진 Hack의 법칙에 기초하여 결정될 수 있었다.

• 융합정보논문지
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• 제10권8호
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• pp.203-212
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• 2020

본 연구는 가상현실(Virtual Reality, VR) 콘텐츠를 활용한 인지재활 프로그램이 노인의 인지기능, 우울감, 상지기능 및 일상생활활동능력에 미치는 영향을 알아보고자 하였다. 연구 집단은 가상현실 인지재활 적용군인 실험군과 보편적 인지자극프로그램 적용군인 대조군으로 나누어 효과성을 분석하였다. 연구결과 MMSE-K 점수가 실험군 13.0%, 대조군 2.3% 향상되었다. 실험군의 영역별 향상도는 MBI 3.1%, MFT(Rt.) 7.1%, MFT(Lt.) 3.5%, K-GDS -25.4%를 나타냈다. 각 집단 간 사전-사후 점수 변화를 비교해 본 결과 일상생활활동능력(p<.001)과 MFT(Rt.)(p<.01)에서 집단 간 유의미한 차이가 있었다. 또한 뇌파를 통해 우울감의 정도를 확인하기 위해 절대 알파파의 변화량을 비교해 본 결과 통계적으로 유의한 차이는 없었지만, 실험군에서 평균값이 양의 값으로 증가하는 결과를 확인할 수 있었다. 이번 연구는 가상현실 콘텐츠를 활용한 인지재활프로그램의 효과성을 검증한 실험으로 노인의 일상생활활동능력, 인지기능, 우울감 및 상지기능을 유지 및 개선하기 위한 새로운 중재방법을 제시한 것에 그 의미가 있겠다.

• 한국실내디자인학회논문집
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• 제23권2호
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• pp.51-61
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• 2014

Aesthetics of use for modern people can be regarded as being weighted toward universal and rational function since it has focused on an 'automation and efficiency' and 'smartness' in terms of technological and human engineering position. Thus, aesthetics of use as an individual agent has remained in minimal level. This study attempts to seek conceptual model of design regarding the behavior of users from the systematization of critical theories about the usability. To do that, 'HERTZAIN TALES' written by Anthony Dune and the concept and system of Droog Design have been used as a core standard. In line with the various experiments by artist groups such as Fluxus, Memphis group and the work of product semantics, and inherent characteristics of Droog design, which has surfaced from the 1990s, concepts that has mentioned in the Hertzain tales have been organized into main texts. By overcoming cognitive bias inherent in the material culture and by overcoming an existing usability based on immateriality and dialectic solution, the autonomy of critical design and instrumentality of Droog design have been systemized. By interpreting the design aspect of 12 pieces that have been submitted to the RE;MIND section, the core of this study, it has been confirmed that conceptual and critical design's aesthetics of use From the interpretation of the design aspect of 12 pieces that have been submitted to the RE;MIND section, the core of this study, it has been confirmed that conceptual and critical design's aesthetics of use has established the autonomy and independence of the behavior of users, created functional articulation of materials and secured new conceptual model and thus, could be an effective methodical clue for creating an emergent design.

• 감성과학
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• 제14권4호
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• pp.617-626
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• 2011

인구 구성층의 고령화가 급진전되고 있는 현 상황에서 고령 사용자를 배려한 사용 편리성이 제고된 제품개발의 필요성이 중요시 되고 있다. 본 연구는 고령자가 일상생활을 유지하는데 있어서 사용 의존도가 높은 가전제품과 기본 기능의 원만한 조작에 불편함을 느끼는 가전제품들을 중심으로 고령자의 사용행동 정황을 분석하고 사용행동순서를 도식화하였다. 그리고 도식화된 순서에 본 조사 대상에 포함되지 않은 다양한 생활가전제품을 대입시켜 최종적으로 4가지 유형의 가전제품 사용자행동모델을 도출하였다. 유니버설디자인 개념과 마찬가지로 신체적 기능능력 특성이 저하된 고령자들도 사용이 편리한 제품 디자인은 그 외 폭넓은 다양한 사용자층에게도 수용될 것으로 기대된다. 도출되어진 사용자행동모델은 제품기획 및 디자인 문제 해결안 탐색을 위한 디자인 프로세스에서 레퍼런스 제공을 목적으로 하고 있다.

• 대한공간정보학회지
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• 제20권4호
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• pp.19-27
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• 2012

RUSLE는 강우침식, 토양침식, 지형적 특징, 경작관리 등과 같은 유역 토양유실량 산정에 널리 사용되어 왔다. RUSLE 관련 매개변수 중 강우침식인자는 가장 민감도가 큰 요소로 그 신뢰성을 높이는 것은 정확한 유역 토양유식량 산정을 위한 필수조건이다. 국내에서는 유역의 토양침식을 조절하고 토양유실량 산정을 위한 강우침식인자 산정에 대한 명확한 기준이 마련되어 있지 않고 연평균 강우량과 침식인자의 관계식을 이용하거나 TRB에서 제안한 방법을 이용하고 있다. 본 연구에서는 빈도분석을 이용하여 강우침식인자를 산정하는 절차를 제안하였다. 다양한 재현빈도와 지속기간에 대해 계산된 강우침식인자는 지속시간에 따라 정규분포 형태로 나타났기 때문에 확률분포함수를 이용해서 강우침식인자를 산정할 수 있도록 적합분포함수를 제안하였다. 본 연구에서 제안한 방법을 통하여 유역의 토양유식을 효과적으로 조절하고 구조물에 대한 설계토양유실량을 계산하기 위한 최적의 강우침식인자를 산정할 수 있을 것으로 사료된다.