• 대한수학교육학회지:학교수학
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• 제14권4호
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• pp.553-564
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• 2012

2007년 개정 교육과정의 초등학교 3, 4학년 수학 익힘책에는 학생들이 수학에 흥미를 느끼게 하고 학습한 내용과 관련된 이야기를 풀어보기 위하여 '이야기 마당'이 신설되었다. 본 논문은 초등학교 3학년 수학 익힘책에 제시된 이야기 마당의 활용 방안에 따른 내용을 분석하고 이에 대한 시사점을 제시하였다. 분석 결과, 이야기의 내용이 해당 단원의 학습 내용과 관련이 없는 경우, 학습자의 수준에서 이야기의 내용 또는 문제를 이해하기 어려운 경우, 학습자의 수준에서 이야기의 내용 또는 문제를 이해하기 어려운 경우, 제시된 문제가 해당 단원의 학습 내용과 관련되지 않은 경우가 나타났다.

• Wind and Structures
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• 제29권2호
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• pp.139-147
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• 2019

One of the most important factors in tall buildings design in urban spaces is wind. The present study aims to investigate the aerodynamic behavior in the square and triangular footprint forms through aerodynamic modifications including rounded corners, chamfered corners and recessed corners in order to reduce the length of tall buildings wake region. The method used was similar to wind tunnel numerical simulation conducted on 16 building models through Autodesk Flow Design 2014 software. The findings revealed that in order to design tall 50 story buildings with a height of about 150 meters, the model in triangular footprint with aerodynamic modification of chamfered corner facing wind direction came out to have the best aerodynamic behavior comparing the other models. In comparison to the related reference model (i.e., the triangular footprint with sharp corners and no aerodynamic modification), it could reduce the length of the wake region about 50% in general. Also, the model with square footprint and aerodynamic modification of chamfered corner with the corner facing the wind could present favorable aerodynamic behavior comparing the other models of the same cluster. In comparison to the related reference model (i.e., the square footprint with sharp corners and no aerodynamic modification), it could decrease the wake region up to 30% lengthwise.

• 보존과학연구
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• 통권25호
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• pp.171-195
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• 2004

This research presents an evaluation of the weathering and deterioration state of the Wanggung-ri five-storied stone pagoda in the Iksan (National Treasure No. 289) and suggests conservational schemes. A deterioration map of the pagoda was drawn from the aspects of petrological, physical, chemical, biological, structural and artificial weathering.The rock properties consisting of the pagoda were medium-grained biotite granite that had leucocratic phenocryst developed in parts. The body of each story suffered severely from the secondary contamination that turned the colors into light grey, pitch dark, yellowish brown, and reddish brown as well as granular decomposition, exfoliation and peel-off. The roof stones were heavy exfoliated or peeled off in most of the cases. In addition to the fine cracks, there were layered cracks on the corners. The roof stones of the3rd and 4th story in the north and west side had some stones fall-off, while those of the 2ndstory in the north side had steel reinforcement filled for a fixing purpose. Those of the 5th story showed big gaps that must have originated from cracks and were easily subject to granular decomposition and rainfall. The inside clay filler was missing in the lower part of the roof stones of the 4th and 5th story and the supporting stones, which were thus covered by light grey or pitch dark sediments. The contact area of the materials was about 70 % in the parts where there was a space due to the filler missing and washigher than 90 % in the lower parts of the pagoda. About 90 % or more of the roof stones surface of each story were covered by aerial plants that formed a thick biological mat. Thus it seemed necessary to come up with the conservational measures to remove the plans living on the surface of the stone materials, with the plans to prevent rain from falling inside, and with the water repellent and hardening treatments to postpone the surface weathering of the rock properties. All those measures and plans must be based on the results of long-term monitoring and thorough detail investigations.

• Steel and Composite Structures
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• 제23권5호
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• pp.571-583
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• 2017

A kind of accordion-web RBS connection, "Tubular Web RBS (TW-RBS)" connection is proposed in this research. TW-RBS is made by replacing a part of web with a tube at the desirable location of the beam plastic hinge. This paper presents first a numerical study under cyclic load using ABAQUS finite element software. A test specimen is used for calibration and comparison of numerical results. Obtained results indicated that TW-RBS would reduce contribution of the beam web to the whole moment strength and creates a ductile fuse far from components of the beam-to-column connection. Besides, TW-RBS connection can increase story drift capacity up to 9% in the case of shallow beams which is much more than those stipulated by the current seismic codes. Furthermore, the tubular web like corrugated sheet can improve both the out-of-plane stiffness of the beam longitudinal axis and the flange stability condition due to the smaller width to thickness ratio of the beam flange in the plastic hinge region. Thus, the tubular web in the plastic hinge region improves lateral-torsional buckling stability of the beam as just local buckling of the beam flange at the center of the reduced section was observed during the tests. Also change of direction of strain in arc shape of the tubular web section is smaller than the accordion webs with sharp corners therefore the tubular web provides a better condition in terms of low-cycle fatigue than other accordion web with sharp corners.

• Earthquakes and Structures
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• 제20권2호
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• pp.149-160
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• 2021

Buildings made using the locally available clay materials are amongst the least expensive forms of construction in many developing countries, and therefore, widely popular in remote areas. It is despite the fact that these low-strength masonry structures are vulnerable to seismic forces. Since transporting imported materials like cement and steel in areas inaccessible by motorable roads is challenging and financially unviable. This paper presents, and experimentally investigates, adobe masonry structures that utilize the abundantly available local clay materials with moderate use of imported materials like cement, aggregates, and steel. Shake-table tests were performed on two 1:3 reduce-scaled adobe masonry models for experimental seismic testing and verification. The model AM1 was confined with vertical lightly reinforced concrete columns provided at all corners and reinforced concrete horizontal bands (i.e., tie beams) provided at sill, lintel, and eave levels. The model AM2 was confined only with the horizontal bands provided at sill, lintel, and eave levels. The models were subjected to sinusoidal base motions for studying the damage evolution and response of the model under dynamic lateral loading. The lateral forcedeformation capacity curves for both models were developed and bi-linearized to compute the seismic response parameters: stiffness, strength, ductility, and response modification factor R. Seismic performance levels, story-drift, base shear coefficient, and the expected structural damages, were defined for both the models. Seismic performance assessment of the selected models was carried out using the lateral seismic force procedure to evaluate their safety in different seismic zones. The use of vertical columns in AM1 has shown a considerable increase in the lateral strength of the model in comparison to AM2. Although an R factor equal to 2.0 is recommended for both the models, AM1 has exhibited better seismic performance in all seismic zones due to its relatively high lateral strength in comparison to AM2.

• Steel and Composite Structures
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• 제25권4호
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• pp.505-521
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• 2017

The steel plate shear wall with beam-only connected infill plate (SSW-BO) is an innovative lateral load resisting system consisting of infill plates connected to surrounding beams and separated from the main columns. In this research, the effects of perforation diameter as well as slenderness ratios of infill plates on the hysteresis behavior of SSW-BO systems were studied experimentally. Experimental testing is performed on eight one-sixth scaled one-story SSW-BO specimens with two plate thicknesses and four different circular opening ratios at the center of the panels under fully reversed cyclic quasi-static loading in compliance with the SAC test protocol. Strength, stiffness, ductility and energy absorption were evaluated based on the hysteresis loops. It is found that the systems exhibited stable hysteretic behavior during testing until significant damage in the connection of infill plates to surrounding beams at large drifts. It is also seen that pinching occurred in the hysteresis loops, since the hinge type connections were used as boundaries at four corners of surrounding frames. The strength and initial stiffness degradation of the perforated specimens containing opening ratio of 0.36 compared to the solid one is in the range of 20% to 30% and 40% to 50%, respectively.

• 지구물리
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• 제4권1호
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• pp.57-69
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• 2001

경상북도 경주시 불국사 삼층석탑(석가탑)의 구조 안전 진단을 목적으로 탑의 각 부재에 대한 비파괴 정밀 조사가 실시되었다. 암석의 역학적 성질을 추정하기 위하여 전체 44개 부재의 456개 지점에서 초음파 속도를 측정하였다. 측정된 속도의 범위는 1217～4403 m/sec의 분포를 가지며 평균 속도는 3227 m/sec이다. 각 부재의 일축 압축강도가 초음파 속도와의 관계를 나타내는 경험식을 이용하여 구하여 졌으며 범위는 134～844 kg/cm^2이고 전체 평균치는 463 kg/cm^2이다. 암석의 파괴강도가 각 부재에서 정상분포를 보인다고 가정하고 석가탑의 각 부재에 대하여 파괴확률을 구하였다. 각 부재가 상위 하중에 의해 전단 파괴가 일어날 확률을 지극히 미약하지만 부재 사이의 접촉면적이 적어 부분파괴의 가능성이 있으며 실제적으로도 접촉면 부근의 모서리 부근에서 부분파괴가 발생하였다. 본 탑의 기단부는 구조적으로 가장 취약하며 하대갑석의 인장 파괴확률은 6～18%로 나타나며 대부분의 부재에서 대각선 방향으로 한 개 이상의 인장 파괴면이 관찰된다.

• 건축역사연구
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• 제22권6호
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• pp.7-22
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• 2013

The purpose of this paper is to study on the spatial characteristics from the "The Holy Trinity" fresco painted by Masaccio in the early Renaissance paintings. The results of this study are as follows. 1. The elevation composition of the "The Holy Trinity" fresco is divided into the upper and lower structure through horizontal axis on horizontal line around vanishing point. The upper structure is composed of vertical axis formed through the disposition of the "Trinity" elements and horizontal axis on horizontal line. The lower structure is composed of the sarcophagus and skeleton in such inside and the altar supported through circular columns of left and right. 2. The section composition of the "The Holy Trinity" fresco is composed of the ceiling structure of cylindrical-shaped vault on upper part around basic square floor plan that is interior space and upper structure. The exterior space and lower structure is placed with sarcophagus in inner part that altar and step is projected as same height and width in the outside direction. 3. The basic floor composition of the "The Holy Trinity" fresco is planned by square shape around structural columns that is placed at corners as symmetry through transverse, longitudinal and diagonal axis. The whole floor composition planned through the altar and step that is in exterior space at front, the apse of round form at rear part and the structure of the middle story concept at interior. 4. The visual aspect of the "The Holy Trinity" fresco is composed of the stable balance in relation with distance and height because the interior and exterior space as well as the upper structure and lower structure is formed by regular proportion system. The elevation angle of visual range was planned to view in detail generally or partially the architectural composition system and element, characters through proper visual distance, center and position.

• 한국전산구조공학회논문집
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• 제27권6호
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• pp.573-580
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• 2014

본 논문에서는 현재 시공중인 58층의 철근콘크리트조 고층건물에서 진동현식게이지를 통해 계측된 기둥의 축방향 변형률과 레이져 스캐닝을 통해 구한 횡변위를 3차원 시공단계해석에 의한 예측치와 비교하였다. 예측치는 ACI 209와 PCA의 재료모델식, PCA report의 축소량 산정알고리즘을 3차원 구조해석 프로그램으로 개발한 ASAP을 사용하여 구하였다. 비교결과 평면의 중앙부 기둥의 축방향 변형율 계측치는 시공단계 해석치와 거의 유사한 결과를 나타내었으나 각 모서리에 두 개씩 배치된 기둥의 경우 비교적 큰 오차를 나타내었다. 레이져 스캐닝에 의한 횡변위 계측결과는 해석결과와 유사한 경향을 보였으나 층당 계측치가 큰 변동을 나타내므로 향후 이를 해결하기 위한 계측 및 데이터 처리기법이 요구된다.

• 항공우주정책ㆍ법학회지
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• 제29권2호
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• pp.205-237
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• 2014

지난 반세기동안 세계 각국에서 쏘아올린 인공위성 등 각종 우주물체들로 인하여 우주환경을 오염시키는 우주폐기물이나 잔해들이 기하급수적으로 늘어나고 특히 지구궤도에 널린 수만개 이상의 고장난 위성과 파편, 쓰레기들은 우주 관측과 위성 송수신에 오류를 일으키거나 우주정거장이나 위성 등 우주비행체와 충돌위험을 야기하고 있다. 예컨대 지난 2009년 2월 기능정지된 위성들인 미국 이리듐사의 통신위성 이리듐 33호와 러시아의 코스모스 2251호의 충돌은 수많은 파편과 더불어 지구와 우주환경에 심각한 위협이 되었으며 또한 2007년 1월 중국에 의한 자국위성 파괴실험은 보다 커다란 우주의 남용 사례로서 우주의 안전을 저해한다는 점에서 국제적인 비난을 불러 일으켰다. 실제로 우주환경이나 폐기물에 관한 문제들이 상당기간동안 과학적 연구와 논의의 대상이 되어온 것은 사실이나 주지하다시피 우주개발의 초기단계에서는 우주활동을 위한 기본 규칙제정을 위한 법적 성격의 규명이나 우주탐사와 이용에 필요한 기준을 마련하는데 주안점을 두어왔다. 따라서 결과적으로 우주활동과정에서 야기될지 모르는 환경훼손의 문제나 위험요소들은 국제우주법의 발전이라는 맥락에서도 우선순위에서 밀렸다는 사실을 지적하지 않을 수 없다. 지금까지 우주폐기물이 우주활동의 양적인 증가와 더불어 늘어났다는 시각외에도 임무실패나 상호 충돌 및 고의적인 파괴나 폭발 등으로 인해 기하급수적으로 증가하고 있다는 사실을 고려할 때 과거에는 뒷전에 밀렸던 우주폐기물 양산에 따른 안전 문제가 차츰 우선적 관심의 대상으로 부각되고 있는 바 이러한 추세는 최근의 UN의 페기물 경감 가이드라인이나 EU 행동규범 등 갖가지 국제협력과 규범화차원의 노력들을 통해 확인할 수 있을 것이다. 이들 가이드 라인이나 행동규범 등 연성법을 통해 각 회원국과 국제기구는 국제적 이행절차 및 각자의 고유한 집행절차에 따라 우주폐기물의 경감에 있어서 가능한 최대한 도로 이행하는 자발적 조치를 취하는 유통성을 부여하고 있다. 본 논문에서는 이런 관점에서 최근 중국에 의한 위성파괴와 관련한 적법성 여하와 국제사회의 우주폐기물에 대한 경감 등 대응 노력과 과제 등을 살펴보고자 하였다.