• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.288-294
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• 2016

The space between tire and wheel guard acts as a path for tire pattern noise transmission. In this study, acoustic phenomenon occurring in the tire-wheel guard space is investigated using acoustic mode analysis and visualization of the sound pressure distribution over the wheel guard surface. We introduced a cavity over the wheel guard surface to reduce the tire pattern noise, where the cavity acts as an acoustic damper. The interior noise was reduced by 2 dB(A), and the noise control measures treated in this study may provide an efficient method to improve interior sound quality without increasing cost and weight at the final stage of the vehicle development.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.2
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• pp.75-88
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• 2017

This study analyzed wind flows based on spatial and geomorphological characteristics of Daegu Metropolitan City. A three-stage analysis was performed, starting with a comparison of meteorological relationships between local wind direction (synoptic wind) and local wind flow. In the second stage the study area was subdivided into districts and suburban districts to analyze the relative change of local wind flow. In stage three, the formation of wind corridor for local wind flow, wind flow for the entire urban space, and spatial relationships between flows were verified comparatively using KLAM_21. Three results are notable, the first of which is a low correlation between synoptic wind of a region, and local wind, flow in terms of meteorology. Secondly, observations of local wind flow at five downtown districts and two suburban districts showed that there were diverse wind directions at each measurement point. This indicates that the spatial and geomorphological characteristics of areas neighboring the measurement points could affect the local wind flow. Thirdly, verifying the results analyzed using KLAM_21, compared to Atomatic Weather System(AWS) measurement data, confirmed the reliability of the numerical modelling analysis. It was determined that local wind flow in a city performs a spatial function and role in ameliorating the urban heat island phenomena. This indicates that, when an urban planning project is designed, the urban heat island phenomena could be ameliorated effectively and sustainably if local wind flow caused by immediate spatial and geomorphological characteristics is confirmed systematically and techniques are intentionally applied to connect the flows spatially within areas where urban heat islands occur.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.420-425
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• 2016

This study discusses the architectural space's phenomenology, focusing on the physical environment and psychological behavior. Kim, Ju-Tae House, which is divided by special relationship, was analyzed by method of constructing space, and behavioral meaning with the perspective of visual structure. Kim, Ju-Tae House was constructed in a clear way by reflecting the users social, and cultural relationship. It has a relational and independent territories by physically surrounding Chae and wall. Each independent limited space is suggesting the space being opened by accessing the space stage by stage. This method of constructing the space makes the user aware of the relative difference from the induced space experience, and recognize the incremental strong isolation. Between the yard, which is located in the center of the house, forms a three-dimensional layer between Sarangchae and Anchae, emphasizing the spacial depth. The physical space is relatively small but because of the environmental conditions, such as the positioning of the observer's perspective, short cycle reorientation, and overlapped layer, it is recognized as far or deep compared to the actual size. This is the relative method as a visual perspective that is intended, and is understood as an active element that induces the psychological attitude by the recognized environment affordability of the user.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.404-404
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• 2011

최근 기상변동성 증가와 극치수문사상의 발생빈도 증가로 인한 기상재해가 빈번하게 일어나고 있다. 이러한 기상현상으로 인한 재해의 예방을 위해서 사전에 위험을 인지하고 그 규모를 예측할 수 있는 여러 기법들이 기상레이더 또는 수치예보자료 등을 이용하여 개발 및 적용되고 있다. 이 과정에서 해결해야 할 여러 문제점들이 있는데, 우선 수치예보자료 또는 기상레이더자료를 종관기상관측소 및 자동기상관측지점의 지상관측 강수량과 연계하여 평가하는 과정이 필요하고, 현재시점에 형성되어 있는 강우장의 공간 이동 예측 기법이 확보되어야 할 것이다. 전북지역은 게릴라성 집중호우가 빈번한 산악형 강수와 산지유역의 급한 하천경사가 맞물려 인명 및 재산피해가 매년 발생하고 있으며, 과거 돌발홍수가 발생한 사례가 있어 이상기후 및 기후변화로 인한 홍수 위험도가 커질 것으로 전망되고 있다. 본 연구는 전라북도의 기상재해 예측모형 개발을 위한 사전 분석과정으로 전라북도지역에서 관측된 기존의 대규모 강수사상을 이용한 강수사상의 특성 분류 및 관측소간 공간상관성을 분석하는데 목적을 두고 있다. 강수사상의 특성분류를 통해 강수 발생형태에 따른 기상학적 영향인자, 강수의 발생량 및 이동특성 예측의 정도를 향상시킬 수 있으며, 분류 기법으로 SVM(support vector machine)을 이용한 자동분류를 적용한다. 또한 관측소간 공간상관성 분석을 위하여 각 관측소 강수량간의 조건부 확률을 이용한다. 예로써 부안관측소에 강수가 발 생했을 때, 부안관측소의 강수량 조건에 의한 전주관측소 강수량 확률을 다음과 같이 구성할 수 있다. �揚滑斂�수량�咀刮활�수량��. 공간상관성 분석과정에서 관측소간 강수 이동시간에 따른 강수 발생 시간의 차이 또한 고려하며, 과거 기상관측 자료의 분석을 통해 전라북도지역의 관측소간 강수발생의 공간적 상관성을 규명하고, 단기예측 모델 개발을 위한 기초자료로 활용할 수 있을 것이다. 또한, 기후변화시나리오에 의한 미래 강수량의 지역적 상세화 과정에도 본 연구를 통한 결과를 이용할 수 있을 것이라 판단된다.

• Korean Journal of Cognitive Science
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• v.10 no.3
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• pp.1-15
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• 1999

Based on known physiological and psychophysical results, a neural network model for visual selection, called FeaureGate is proposed. The model consists of a hierarchy of spatial maps. and the flow of information from each level of the hierarchy to the next is controlled by attentional gates. The gates are jointly controlled by a bottom-up system favoring locations with unique features. and a top-down mechanism favoring locations with features designated as target features. The present study focuses on the top-down mechanism of the FeatureGate model that produces results similar to Moran and Desimone's (1985), which many current models have failed to explain, The FeatureGate model allows a consistent interpretation of many different experimental results in visual attention. including parallel feature searches and serial conjunction searches. attentional gradients triggered by cuing, feature-driven spatial selection, split a attention, inhibition of distractor locations, and flanking inhibition. This framework can be extended to produce a model of shape recognition using upper-level units that respond to configurations of features.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.1
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• pp.39-51
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• 2004

This study aims to suggest new algorithm, named as Simoo, in order to improve spatial conflicts and vector displacement between linear features in generalization of the linear features. Main principles of Simoo algorithm is adoption of simplification and smoothening methods. Tolerance conditions used in Simoo are perpendicular length, external angle, and average vertex length. Main characteristics of Simoo are the application of scale, cartographic refinement, minimization of logical errors, and maintenance of geographical properties. The Simoo was applied through comparison to existing Douglas-Peucker algorithm. Resultantly, maintenance ratios of line such as coastal line and stream network were over 97% in both algorithms. The elimination ratio of vertex points may be more effective in Douglas-Peucker than in Simoo. Spatial conflicts between linear features may be more minimized in Simoo. The curvature and smoothening of lines become decreased in scale in application of Simoo. Finally, Simoo algorithm may be more effective than Douglas-Peucker for cartographic generalization.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.429-429
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• 2011

우리나라는 연중 강우량의 계절적 편중이 심하여 약 2/3이 6월-9월에 집중하는 기상학적 요인과, 국토의 약 70%가 산악지역으로 되어있는 지형학적 요인 등 홍수에 취약한 자연특성을 갖고 있으며, 특히 하천, 도시 저지대, 해안 및 산지에서는 홍수범람, 내부배제 불량, 해일, 산사태 등으로 매년 많은 인명피해와 재산상의 손실이 크게 발생하고 있다. 또한 최근 발생하고 있는 이상기후 현상과 각종 개발사업으로 인한 불투수면적의 증가 등으로 인해서 극한 홍수의 발생빈도가 높아가고 있으나, 기존 수방시설물의 홍수배제능력 부족 등으로 매년 많은 피해를 입고 있는 실정으로, 구조적인 대책만으로는 재해피해를 경감시키는데 한계가 있음을 인식하여 구조적 대책과 더불어 토지이용규제 및 개발규제, 홍수터관리, 홍수예경보 등 비구조적 재해대 비능력 향상이 시급한 현황이다. 우리나라의 경우, 구조적 수방기술의 발전은 비교적 높은 수준에 도달해 있지만, 구조적 대책에 비해 비구조적 대책의 개발 및 적용은 미흡한 형편이므로, 비구조적 홍수대책의 종합적 정비 및 효율적 운영방법 필요하다. 따라서 본 연구에서는 홍수유형별 발생원인별 대표적인 비구조적 홍수대책을 국내외 적용사례를 조사하여 분석하고, 비구조적인 홍수방어대책들에 대한 장단점 및 적용성 등의 정성적 평가를 실시하였다. 국내 여건에 적합한 홍수위험구역 설정방안을 제시하고자, 국내의 다양한 하천공간 확보를 위한 관련규정인 하천구역, 홍수관리구역, 수변구역, 상수원보호구역, 친수구역, 홍수위험구역, 자연재해위험지구, 방재지구 등에 대하여 조사하였으며, 국외 사례로 영국의 홍수위험구역 평가제도, 미국의 홍수터 관리 프로그램, 호주의 하천공간 분류 기준, 일본의 하천공간 설정 기준 등에 대한 고찰을 수행하였다. 또한 국내 홍수보험 제도의 문제점 분석 및 제고방안을 제시하고자, 현재 소방방재청 주관으로 시행되고 있는 풍수해보험제도에 대한 조사 및 분석을 실시하였으며, 미국에서 시행되고 있는 국가홍수보험프로그램, 프랑스의 자연재해보험, 스위스의 자연재해보험풀 제도, 일본의 홍수보험제도에 대하여 심층적인 고찰을 수행하였다.

• Journal of the Korean earth science society
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• v.40 no.1
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• pp.86-106
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• 2019

The purpose of this study is to develop an astronomy education program reflecting astronomical thinking to be used at science museum and to investigate the effect of the program on the improvement of astronomical thinking ability of high school students. After selecting the components of astronomical thinking through literature studies, we developed an astronomy education program consisting of four stages: demonstration and observation, and question and thinking, support and group discussion, demonstration and assessment. In order to verify the effectiveness of the program, we conducted a covariance analysis on the pre- and post-tests of the experimental group and control group to examine the level of students' thinking before and after using the program in teaching and learning. As a result, it was confirmed that the astronomy education program reflecting astronomical thinking was effective in promoting students' astronomical thinking ability. In particular, this program was effective in enhancing the ability of modeling by reconstructing the observed astronomical phenomenon from the viewpoint of the universe with respect to spatial thinking in the astronomy domain. It was also effective to improve the ability of organizing the system by grasping the relationship between the elements constituting the astronomical system in relation to the system thinking in the astronomy domain. This study is significant in suggesting a specific teaching and learning program to develop students' astronomical thinking.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1595-1611
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• 1994

In this paper, the numerical wave propagation properties of the finite difference-time domain(FD-TD) method is investigated as a discrete model describing electromagnetic(EM) wave propagation phenomena. The leap-frog approximation of Maxwell's curl equations in time-space simulates EM wave propagation in terms of the numerical characteristic and the domain of dependence. A geometrical interpretation of the FD-TD numerical procedure is presented. The numerical dispersion error due to the leap-frog approximation and its dependence on the stability factor are illustrated. The FD-TD method using the leap-frog approximation is inherently a descriptive model. Thus, not only any physical picture about EM wave propagation phenomena can be drawn through this model, but also physical or engineering parameters in the frequency domain can be extracted from descriptive results. E-plane filter characteristics in the WR-28 rectangular waveguide and reflection property of an inductive iris in the WR-90 rectangluar waveguide extracted from simulation of the FD-TD model is included.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.95-109
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• 2002

A significant question is what role does newly-formed expansive mineral growth play in the premature deterioration of concrete. These minerals formed in cement paste as a result of chemical reactions involving cement paste and coarse/fine aggregate. Petrographic observations and SEM/EDAX analysis were conducted in order to determine chemical and mineralogical changes in the aggregate and cement paste of samples taken from lowa concrete highways that showed premature deterioration. Formation and expansive mechanisms involved in deterioration were Investigated. Brucite, Mg(OH)$_2$, is potentially expansive mineral that farms in cement paste of concretes containing reactive dolomite aggregate as a result of partial dedolomitization of the aggregate. No cracking was observed to be spatially associated with brucite, but most brucite was microscopic in size and widely disseminated in the cement paste of less durable concretes. Expansion stresses associated with its growth at innumerable microlocations may be retrieved by cracking at weaker locations in the concrete. Ettringite, 3CaO.Al$_2$O$_3$.3CaSO$_4$.32$H_2O$, completely fills many small voids and occurs as rims lining the margin of larger voids. Microscopic ettringite is common disseminated throughout the paste in many samples. Severe cracking of cement paste causing premature deterioration is often closely associated with ettringite locations, and strongly suggests that ettringite contributed to deterioration. Pyrite, FeS2, is commonly present in coarse/fine aggregates, and its oxidation products is observed in many concrete samples. Pyrite oxidation provides sulfate ions for ettringite formation.