• International Journal of Highway Engineering
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• v.13 no.4
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• pp.81-91
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• 2011

This study was conducted to evaluate the necessity of the anchor lug system in continuously reinforced concrete pavement(CRCP) by comparing longitudinal displacements of CRCPs with and without anchor lugs, and to investigate the effect of horizontal cracking on CRCP performance by measuring the vertical displacements. The measurements before and after the anchor lug section was separated were conducted for 12 days in June, and for 14 days in August after the abrupt displacements according to cutting disappeared, respectively. This short term measurement results showed that when anchor lugs were installed, a daily displacement variation at any location was less than 0.1mm; therefore, longitudinal movements were negligibly small. When there were no anchor lugs, longitudinal displacements mainly occurred near the free end and the displacement variation was small; therefore, an expansion joint system seems to be employed at a CRCP terminus without installing anchor lugs. However, further studies are needed to verify the terminus behavior due to annual temperature changes. The horizontal crack width variation was ignorable and did not affect the vertical displacement of the slab. Therefore, the horizontal crack did not delaminate the slab and did not seem to reduce the structural capacity and performance of CRCP.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.251-261
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• 2007

This study is to investigate the damage assessment of adjacent structures due to tunneling in urban environment. Model tests were carried out with two-story masonry building structures in various shapes and locations. The damage level of adjacent structures were very differently estimated in accordance with the shape ratio (L/h) of structures, construction stages, and various locations. The results of model tests were plotted on the damage level graphs in order to predict the direction of damage levels for the different types of structures (i.e. stiffness of structures, L/h). The progressive crack development mechanism at various construction stages was revealed through model tests and crack size indicated more conservative side of damage level on the damage level graph.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.104-110
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• 1995

지반과 구조물의 동적 상호작용은 건설분야에서의 중요한 현상으로, 특히 지반을 통해 인근구조물로 전달되는 진동은 구조물 자체의 구조적인 문제 뿐 아니라 그 속에 거주하는 사람이나 설비에 대한 안전성 또는 사용성에 나쁜 영향을 야기할 수 있다. 본 논문에서는 이러한 진동을 저감시키기 위해, 지반내에 정상적인 진동전파를 방해하는 구조물을 시공하여 진동 저감효과를 만들어 내는 방법을 연구하였다. 이러한 연구의 발상은 다음과 같다. 충진지반에서의 지반진동의 진폭을 해석하면서 진동의 크기가 기저암의 위치에 따라 큰 영향을 받는 것을 알았고 이로부터 지반내에 인위적인 층을 만들수 있다면 지반진동의 크기를 변화시킬 수 있지 않을까라는 생각에서 본 연구를 시작하였다. 또한 지반 내에서의 정상적인 진동의 전파를 방해하기 위한 차진 구조물을 만드는 방법은 연약지반의 강도중대 또는 차수의 목적으로 주로 사용하고 있는 그라우팅공법의 사용이 가능할 것이므로, 기존의 그라우팅현장에서 만들어진 지반의 물성치들을 사용하여 경계요소법에 의한 수치해석적 방법을 택하였다. 본 연구에서는 그라우팅공법의 시공성에 관한 것은 포함되지 않는다. 본 논문에서는 지반의 구조를 경사구조와 수평지반구조라는 두가지 특징적인 경우에 대해 검토하였다. 이중 경사진 기저암층을 가진 지반의 경우에는 기저암에서 진동의 비대칭적인 반사에 의해 수평기저암에서와는 달리 기저암의 한쪽에서 다른쪽에 비해 큰 진동이 발생한다. 그라우팅층의 효과를 검토하기 위한 연구의 순서는 일정주파수의 조화진동에 대해 먼저 여러 가지 크기의 그라우팅층과 함께 블록으로 볼 수 있는 크기의 그라우팅층에 대해 진동저감효과를 해석하였고, 이를 통해 보강층의 소요크기 및 최적위치를 구하였다. 사용된 물성치는 실제 지하철 건설현장에서 나타난 지반물성치 및 그라우팅후의 지반강도 및 전단파전파속도를 이용하였다. 또한 마지막에서 검토된 기차하중에 대한 효과를 알아보기 위해 사용된 기차운행에 의한 지반가속도도 역시 측정된 값을 사용하였다. 그러나 당시의 기차운행속도가 낮아 정상적인 운행에서는 더 큰 값이 나올 것으로 판단되었으나 측정된 값을 그대로 사용하였다.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.20-20
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• 2010

강원도 태백 지역에 위치한 조선누층군의 세송층을 대상으로 암상변화, 해수면 변화, 안정탄소동위원소 층서를 조사하였다. 세송층은 중기에서 후기 캄브리아기에 속하는 지층으로서 직동지역과 사군다리지역에서 조사하였다. 직동지역의 세송층은 수평층리 이회암상, 리본 석회암상, 단괴 석회암상, 수평층리 사암상, 석회역암상으로 구성되어 있으며, 이들은 내부완사면, 중부완사면, 외부완사면의 세개의 상조합으로 분류되었다. 세송층의 하부로부터 약 30m 까지는 리본석회암상과 석회역암상, 일부 단괴석회암상이 나타나는 구간으로 중부완사면 환경에서 퇴적된 것으로 해석되며, 약 30m부터 42m 까지는 점차 이회암상의 비율이 증가하여 상향 세립화의 경향성을 보이는 구간으로 외부완사면 환경에서 퇴적된 것으로 해석된다. 사군다리 지역은 세송층의 상부가 나타나는 곳으로 평행엽층리사암상과 단괴석회암상이 관찰되며 중부완사면 환경에서 퇴적된 것으로 해석된다. 세송층의 석회암은 하부 이암, 중부 와케스톤, 상부 와케스톤과 팩스톤으로 변화하는 것으로 관찰되었다. 세송층에서의 안정탄소동위원소 잘량 분석결과 양의 값(2.5-3.0‰)을 보이는 Peak 구간이 하부로부터 25m 높이 부근에서 존재하는 것으로 나타났다. 이러한 분석결과는 Steptoean 시기(약 496 Ma)에 전 지구적으로 발생했던 안정탄소동위원소 값의 양(positive)의 변동을 반영한 SPICE(Steptoean positive carbon isotope excursion) 구간에 해당되는 것으로 해석된다. SPICE 구간은 세송층의 중상부에 해당하는 곳으로 와케스톤, 팩스톤의 석회암을 포함하는 석회역암상, 단괴 석회암상으로 구성되어 있으며 이는 상대적으로 해수면이 낮았던 시기를 지시한다. 이러한 SPICE는 큰 규모의 전 지구적 탄소순환의 변동을 대표하며 대륙 간의 대비를 용이하게 하고 퇴적당시의 환경적 변화를 해석하는데 도움을 준다. 북중국과 북미 Laurentia의 안정탄소동위원소 값을 비교해보면 두 지역 모두 세송층과 유사한 값을 보인다. 다만 북중국 지역은 Chuangia Zone에서 SPICE가 나타나는 반면 세송층은 Prochuangia Zone에서 SPICE가 나타난다는 차이가 있다.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.304-315
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• 2016

In this study, the current horizontal stress characteristics of the Tertiary rock formations in the Pohang Basin are investigated on the basis of the in-situ rock stress measurements at depths from 75 m to 716 m of the 3 test boreholes in the Doumsan area, Pohang. The deep hydraulic fracturing stress measurement results indicated that the horizontal stress components in the test site appear far lower than the average ones by the linear fit for the data set measured from the other domestic sites. But, borehole scanning revealed clearly that lots of small and large scale borehole failures occurred due to the low strength characteristics of the existing rocks. To obtain more accurate and overall information on the horizontal stress direction, the integrated analysis combining the hydraulic fracturing stress measurement and borehole scanning data set were additionally carried out. The analysis results showed that in the upper sedimentary and the lower volcanic rock formation, the dominant orientations of the current maximum horizontal stress components were appeared in the range of $80^{\circ}{\sim}100^{\circ}$ (N80E~N80W) and $120^{\circ}{\sim}140^{\circ}$ (N60W~N40W), respectively. From this study result it was found that the maximum horizontal stress directions have a tendency to rotate in a clockwise direction as the rock formation changes with depth in the test site.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.124-135
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• 2011

The capacity of bearings installed at abutments and piers for continuous bridges is usually determined by the magnitude of the maximum vertical reaction at each support and the capacity of bearings placed at piers is higher than that at abutments. In this study, the possibility of the improved seismic performance of base-isolated continuous skew bridges was investigated by analysing the variation of the seismic behavior of them according to three arrangements of bearings. Based on the conventional arrangement of bearings(Case A), three arrangements of bearings such as Case A, Case B and Case C were selected considering the variation of the horizontal stiffness of the lead rubber bearing(LRB) installed at the pier. The seismic behavior of the total 36 skew bridges was investigated by conducting the response spectrum analysis using the hybrid response spectrum considered the effect of LRB's damping. Results of analyses show that a more desirable seismic behavior of base-isolated continuous skew bridges can be obtained by reducing the magnitude of the horizontal stiffness of LRB placed at the pier to similar to or less than that of LRB installed at abutments. The variation of LRB's stiffness at the pier brings about period elongation and the change of mode shapes of base-isolated skew bridges and results in the reduction of the total base shear, the maximum base shear at the pier and the girder stresses. Although positive effects on the seismic behavior of base-isolated skew bridges caused by the change of arrangement of bearings decreased slighty with an increase in the flexibility of the substructure, the proposed arrangements of bearings bring about the improved seismic performance of base-isolated continuous skew plate girder bridges with less than 10m height of piers.

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.691-697
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• 2005

Recently, the development of accurate gravity-meter and GPS make it possible to obtain high resolution gravity data. Though gravity data interpretation like modeling and inversion has significantly improved, gravity data processing itself has improved very little. Conventional gravity data processing removes gravity effects due to mass and height difference between base and measurement level. But, it would be a biased density model when some or whole part of anomalous bodies exist above the base level. We attempted to make a multiquadric surface of the survey area from topography with DEM (Digital Elevation Map) data. Then we constituted rectangular blocks which reflect real topography of the survey area by the multiquadric surface. Thus, we were able to carry out 3-D inversions which include information of topography. We named this technique, 3-D Gravity Terrain Inversion (3DGTI). The model test showed that the inversion model from 3DGTI made better results than conventional methods. Furthermore, the 3-dimensional model from the 3DGTI method could maintain topography and as a result, it showed more realistic geologic model. This method was also applied on real field data in Masan-Changwon area. Granitic intrusion is an important geologic characteristic in this area. This method showed more critical geological boundaries than other conventional methods. Therefore, we concluded that in the case of various rocks and rugged terrain, this new method will make better model than convention ones.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.217-217
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• 2003

W-Cu 합금은 우수한 전기적, 열적 특성으로 인하여 열소산재료(Heat sink)로 많이 응용되고 있다. 첨단 전자부품 이외에도 핵융합로의 Diverter가 그 예로서, 내부는 고강도와 고융점의 특성을 요구하는 반면, 외부는 높은 열전도성을 필요로 한다. 그래서 동일한 조성의 일반적인 W-Cu 합금보다 W과 Cu의 조성이 점차적으로 변화하는 경사기능재료(Functionally Graded Materials)가 냉각효율이 클 것으로 기대된다. 현재, W-Cu FGM에 대한 많은 연구가 진행되고 있지만, 그 조성이 연속적으로 변화하는 W-Cu FGM에 대한 연구는 전무한 실정이다 본 연구에서는 방전플라즈마 소결장치(Spark Plasma Sintering System)와 용침고정을 이용하여 연속적인 조성변화를 갖는 W-Cu FGM을 제조하고 그 특성에 관해 분석하고자 하였다. 소결체가 밀도 변화를 갖게 되도록 제작한 특수 경사기능 몰드에 W분말을 장입한 후, 15㎬의 압력하에서 SPS를 이용하여 W소결체를 제조하였다. 제조된 W소결체는 수평관상로에서 수소분위기 하에 Cu 용침을 실시하여 W-Cu FGM을 제조하였다 SEM을 이용한 각 위치별 조직관찰과 Image Analyzer를 이용한 W과 Cu의 면적비, 그리고 비커스경도계에 의한 경도 측정을 실시하였다. 또 열기계적 분석기를 이용하여 측정된 선팽창률로부터 열팽창계수를 구하였다. 80$0^{\circ}C$에서 ？칭하는 반복적인 싸이클을 통해 열충격시험을 실시하였고, Laser flash method로 열확산계수를 측정하였다.

• Journal of the Mineralogical Society of Korea
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• v.16 no.3
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• pp.265-280
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• 2003

The Mugeuk mineralized area that associated with the pull-apart type Cretaceous Eumseong basin is composed of several gold-silver vein deposits that are emplaced in late Cretaceous biotite granite. The gold-silver deposits in the area show various hydrothermal alteration zones as well as Au/Ag ratios and ore mineralogy. The Geumbong mine showing relatively high gold fineness is composed of multiple veins and show alteration pattern; vein \longrightarrow phyllic \longrightarrow subphyllic \longrightarrow propylitic \longrightarrow subpropylitic zone. In contrast, The Taegeuk mines show the low fineness values, in far southern part are characterized by increasing tendency of simple and/or stockwork veins. The deposit displays alteration pattern; vein \longrightarrow propylitic \longrightarrow subpropylitic zone. Variations of alteration zone with depth show that phyllic zone are dominant in deeper level and propylitic zone sporadically overlapped by argillic zone are dominant in shallow level. The differences of alteration pattern between the gold-silver deposits are reflect the evolution of the hydrothermal fluids; the ore-forming fluids of the Geumbong mine are at relatively high temperature and salinity and highly-evolved meteoric water, developing phyllic zone, the Taegeuk mine containing greater amounts of less-evolved meteoric waters shows relatively low temperature and salinity in ore-forming fluids, developing propylitic zone. The various physicochemical environment for gold-silver mineralization in the Mugeuk mineralized area is due to proximity from heat source area (Mugeuk mine) to marginal area (Taegeuk mine) in a geothermal field. Therefore, it is suggested that the criteria for project exploration in the area are to focus on the area proximal to heat source and phyllic zone.

• Korean Journal of Cognitive Science
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• v.10 no.3
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• pp.51-66
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• 1999

Selective attention induces perceptual distortions. ranging from repulsion of objects located near the attended area(Suzuki & Cavanagh. 1997) to magnification of the u unattended objects (Tsal & Shalev. 1996). Two hypothetical mechanisms have been p postulated: a shift of receptive fields' positions away from the locus of attention(receptive-field-recruitment hypothesis) or the enlargement of perceived space around the a attended location(space-enlargement hypothesis). The present study distinguished between these hypotheses by investigating the spatial and temporal properties of attention-induced d distortions. Perceptual judgements on vernier alignment. line tilt. line length were used to measure attention-induced changes in perception. Attention was induced exogenously(by blinking a specific set of dots around the test stimuli} or endogenously(by instructing the subject to selectively attend the dots). After inducing attention. the test stimuli were briefly flashed. A staircase method was used to measure the attentional effect. A vertical line was perceived as repelled from the locus of attention. and a line segment appeared longer when attention was given to its vicinity. The effects decreased as the distance between the locus of attention or the time between the onset of attention and the stimulus presentation increased. The results imply that the space-enlargement hypothesis provides a better explanation for the attention-induced changes in perception than the receptive-field-recruitment hypothesis.