• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.57-58
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• 2006

The effects of lowering ECAP temperature during ECAP process and Post-ECAP annealing on microstructure, texture and mechanical properties of the AZ31 alloys have been investigated in the present study. The as-extruded materials were ECAP processed to 2 passes at 553K prior to subsequent pressing up to 6 passes at 523K or 493K. When this method of lowering ECAP temperature during ECAP was used, the rods could be successfully deformed up to 6 passes without any surface cracking. Grain refinement during ECAP process at 553K might have helped the material to endure further straining at lower deformation temperatures probably by increasing the strain accommodation effect by grain boundary sliding, causing stress relaxation. Texture modification during ECAP has a great influence on the strength of Mg alloys because HCP metals have limited number of slip systems. As slip is most prone to take place on basal planes in Mg at room temperature, the rotation of high fraction of basal planes to the directions favorable for slip as in ECAP decreases the yield stress appreciably. The strength of AZ31 Mg alloys increases with decrease of grain size if the texture is constant though ECAP deformation history is different. A standard positive strength dependence on the grain size for Mg alloys with the similar texture (Fig. 1) supports that the softening of ECAPed Mg alloys (a negative slope) typically observed despite the significant grain refinement is due to the texture modification where the rotation of basal planes occurs towards the orientation for easier slip. It could be predicted that if the original fiber texture is restored after ECAP treatment yielding marked grain refinement, yield stress as high as 500 MPa will be obtained at the grain size of ${\sim}1{\mu}m$. Differential speed rolling (DSR) with a high speed ratio between the upper and lower rolls was applied to alter the microstructure and texture of the AZ31 sheets. Significant grain refinement took place during the rolling owing to introduction of large shear deformation. Grain size as small as $1.4{\mu}m$ could be obtained at 423K after DSR. There was a good correlation between the (0002) pole intensity and tensile elongation. This result indicates that tensile ductility improvement in the asymmetrically rolled AZ31 Mg alloys is closely related to the weakening of basal texture during DSR. Further basal texture weakening occurred during annealing after DSR. According to Hall-Petch relation shown in Fig. 1, the strength of the asymmetrically rolled AZ31 is lower than that of the symmetrically rolled one when compared at the same grain size. This result was attributed to weakening of fiber texture during DSR. The DSRed AZ31, however, shows higher strength than the ECAPed AZ31 where texture has been completely replaced by a new texture associated with high Schmid factors.

• 한국전통조경학회지
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• 제32권4호
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• pp.120-131
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• 2014

조선 개국 시 영조된 사직단은 일제강점기를 거치면서 사직공원으로 고착화되었고, 최근 복원에 대한 노력이 진행되고 있다. 통시적으로 분석된 사직단의 변화 내용은 다음과 같다. 첫째, 한 나라의 중요 국가제사를 지내던 장소로의 입지를 확보하고 강화되었던 조선시대 태조에서 일제강점기 이전까지의 시기이다. 태조대에 인왕산 자락에 축조했으며 임진왜란 시 소실된 후 영조 대에 제례시설이 완비되었다. 그러나 1908년 일제의 간섭이본격화되자 공간 멸실과 제사가 폐지되었다. 둘째, 일제에 의해 공원화가 진행되어 고착화된 1910년부터 1944년까지이다. 공원 관련 시설과 경계부에 이질적인 건축물이 들어섰고, 단 영역 재실 사직단문이 고적과 보물로 지정되기도 하였다. 셋째, 해방 이후 1984년까지 이질적 성격의 동상과 기념비, 건축물이 축조되어 혼재된 장소성을 지니게 된 시기이다. 사직터널의 개설로 사직단 문이 2번에 걸쳐서 이축되기도 하였다. 넷째, 사직단의 역사성과 상징성을 회복하기 위한 노력이 진행되고 있는 1985년부터 현재까지이다. 사직단 권역의 복원 계획이 진행되고 있으나 주민에 대한 반발로 난항을 겪고 있는 시기이기도 하다. 향후, 사직단의 원형 회복을 위한 복원을 위해서는 발굴조사를 통한 면밀한 고증과 주민의 이해가 함께 진행되어야 한다.

• 한국전통조경학회지
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• 제32권2호
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• pp.55-67
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• 2014

조선시대 경강 동호지역은 역사와 문화적 요소가 풍부하여 역사문화경관의 명승명소가 많았으나 현대 한강은 자연경관에 비해서 문화성과 역사성이 낮은 것으로 인식되고 있다. 본 연구는 한강이 지니고 있는 역사문화적 요소를 한강의 경관에 적용하고자 조선시대 문화공간의 경관 특성을 린치의 시각적 이미지요소에 적용하여 경관특성을 살펴보았다. 연구결과는 다음과 같다. 동호를 시각적 이미지 요소에 적용했을 때 '통로'로서 높게 인식되었고 가장자리를 의미하는 '경계'의 명료성 또한 동호가 높게 인식되었다. 방향 전환점인 '결절점'은 두모포가 인지도에서 우수하게 나타났다. 린치의 시각적 이미지 요소에서 '랜드마크'를 문화공간에 적용했을 때 경강 동호, 압구정, 제천정이 우월한 인지도를 보임으로써 역사문화경관의 지명도와 명성은 시각적 이미지 요소에 비례하는 것으로 파악되었다. 문화공간의 패턴, 구조, 의미가 명료하고 정체성이 확실할수록 '랜드마크'와 '지역'요소가 높게 인식되었다. 공간의 지명도가 높을수록 역사문화경관의 인지도가 높았다. 그러므로 한강의 역사문화경관 복원 시 시각적 인지도를 고려하여 조사하고 사례연구 함으로써 장소의 복원과 함께 역사성과 문화성에 대한 인지도를 높일 수 있을 것으로 사료된다.

• 말소리와 음성과학
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• 제5권1호
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• pp.109-121
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• 2013

This study examined several kinematic properties of the primary articulator (the tongue dorsum) and the supplementary articulator (the jaw) in the articulation of the voiceless velar stop (/k/) within nonassimilating contexts. We examined in particular the spatiotemporal properties (constriction duration and constriction maxima) from the constriction onset to the constriction offset by analyzing a velar (/k/) followed by the coronal fricative (/s/), the coronal stop (/t/), and the labial (/p/) in across-word boundary conditions (/k#s/, /k#t/, and /k#p/). Along with these measurements, we investigated intergestural temporal coordination between C1 and C2 and the jaw articulator in relation to its coordination with the articulation of consonant sequences. The articulatory movement data was collected by means of electromagnetic midsagittal articulometry (EMMA). Four native speakers of Seoul Korean participated in the laboratory experiment. The results showed several characteristics. First, a velar (/k/) in C1 was not categorically reduced. Constriction duration and constriction degree of the velar (/k/) were similar within nonassimilating contexts (/k#s/=/k#t/=/k#p/). This might mean that spatiotemporal attributes during constriction duration were stable and consistent across different contexts, which might be subsequently associated with the nontarget status of the velar in place assimilation. Second, the gestural overlap could be represented as the order of /k#s/ (less) < /k#p/ (intermediate) < /k#t/ (more) as we measured the onset-to-onset lag (a longer lag indicated shorter gestural overlap.). This indicates a gestural overlap within nonassimilating contexts may not be constrained by any of the several constraints including the perceptual recoverability constraint (e.g., more overlap in Front-to-Back sequences compared to the reverse order (Back-to-Front) since perceptual cues in C1 can be recovered anytime during C2 articulation), the low-level speech motor constraint (e.g., more overlap in lingual-nonlingual sequences as compared to the lingual-lingual sequences), or phonological contexts effects (e.g., similarity in gestural overlap within nonassimilating contexts). As one possible account for more overlap in /k#t/ sequences as compared to /k#p/, we suspect speakers' knowledge may be receptive to extreme encroachment on C1 by the gestural overlap of the coronal in C2 since it does not obscure the perceptual cue of C1 as much as the labial in C2. Third, actual jaw position during C2 was higher in coronals (/s/, /t/) than in the labial (/p/). However, within the coronals, there was no manner-dependent jaw height difference in C2 (/s/=/t/). Vertical jaw position of C1 and C2 was seen as inter-dependent as higher jaw position in C1 was closely associated with C2. Lastly, a greater gap in jaw height was associated with longer intergestural timing (e.g., less overlap), but was confined to the cluster type (/kp/) with the lingual-nonlingual sequence. This study showed that Korean jaw articulation was independent from coordinating primary articulators in gestural overlap in some cluster types (/k#s/, /k#t/) while not in others (e.g., /k#p/). Overall, the results coherently indicate the velar stop (/k/) in C1 was robust in articulation, which may have subsequently contributed to the nontarget status of the velar (/k/) in place assimilation processes.

• 농촌계획
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• 제23권1호
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• pp.53-63
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• 2017

Although some indicators for evaluating rural settlement conditions have been offered, these indicators could not reflect unique characteristics that rural has its own peculiarities. The rural area is identified with central districts functioned as service provision and hinterlands used its service. The aim of this study is to find a central district of rural villages and define range of its hinterlands using various physical characteristics of rural areas. Targeting areas are Yongsan and Hwanggan in Yeongdong-gun. The physical characteristics are represented by building density, number of shops among secondary and tertiary industries, official land price, and density of bus line. The rural central district is estimated by linear programming using defined the physical characteristics. Also its hinterlands used Huff model and social accessibility. The results of this study are as follows; (1) The physical characteristics in Hwanggan myeon is higher than Yongsan myeon because Hwanggan area has a large floating population for using Hwanggan station and ticket office; (2) The central district in Hwanggan has wider regional range than Yongsan. When central district estimate in rural areas, we suggest a grid diameter of Hexagon for controlling errors; (3) Considering accessibility, the life zone of 4 districts defined legally in Hwanggan use Yongsan and 2 legal districts in Hwanggan are possible to take advantage of Yongsan's life zone; (4) The results of survey targeting boundary villages between Yongsan and Hwanggan, individual drivers use central districts both Yongsan and Hwanggan, however users by public transportation (especially bus) go more to Hwanggan because bus lines to Hwanggan have many routes than to Yongsan. Evaluating the rural settlement conditions by national unit through grasping central districts and its hinterlands, these results can use as base line data and the evidence for regional development projects.

• 한국조경학회지
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• 제38권1호
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• pp.98-106
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• 2010

방선문(訪仙門)은 한라산의 옛 이름인 영주산을 신비롭게 하는 신선사상의 흔적이 가장 역력한 명소로 한천계곡에 자리잡고 있다. 영주십경의 하나인 '영구춘화(瀛丘春花)'의 대상장으로 널리 알려진 방선문(訪仙門)과 들렁귀(등영구(登瀛丘))는 문자 그대로 '신선이 사는 곳으로 들어가는 문'이라는 뜻이며, 신선의 산 영주산으로 이르는 통로이자 속세와 탈속의경계로 그려지고 있다. 조선조 선비들은 신선의 고향 한라산을 무대 삼아 방선문, 환선대, 우선대 그리고 등영구의 제액(題額)을 바위에 각자(刻字)함으로써 신선의 문에 들어, 신선을 부르고, 신선을 만나, 신선의 세계로 오르는 선경의 이미지를 방선문에 구축해 왔다. 이는 세속의 번거로움을 털고 한라산 신선이 되는 풍류 행위의 시적 표현이며, 도교적 이상세계에 대한 염원으로, 방선문 4승경의 장소 정체성을 이루는 핵심이다. 방선문이 갖는 선경적 장소성뿐만 아니라 계곡 및 하천경 관을 이루는 지질지형학적 특성과 식물생태학적 가치는 방선문이 '자연경관으로서 명승'으로도 부족함이 없음을 보여준 다. 고찰 결과를 종합할 때 방선문은 마애각에 새겨진 제영의 의미가 갖는 장소정체성과 선경적 의미 그리고 영주십경의 대상장이자 '영구춘화'의 시점장으로서는 물론 방선문 계곡의 자연적 아름다움을 바탕으로 선인과 자연과의 만남을 통한 교감의 장소로 유전되어 왔다. 지금도 제주민과 호흡하는 문화공간으로 지속되고 있음은 생활명승의 전형성 또한 동시에 보여주고 있다. 따라서 현재 문화재보법의 명승적 가치와 기준으로 보았을 때 제주 방선문계곡은 명승의 조건에 가장 부합되는 전형적 장소이자 공간이라 할 만하다.

• 한국환경복원기술학회지
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• 제5권5호
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• pp.58-66
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• 2002

We present a planting plan of the buffer-forest belts created at the boundary area of the waste landfill site which is located in the coastal area of Kyubg-Gi province. In order to form a proper section of ground soil excavated from the sea and a forest which shows a distinction of the vegetation stratification, the planting plan with trees, sub-trees, shrubs, and seedlings (produced at a sprout cultivation place) is devised with an adjustment of planting density. 1. The preparation of mounding is required for planting at a waste landfill site. We first estimate an economical and efficient banking height together with the quantity of soil, and prepare a planting ground with excavated ground soil for the consideration of soil recycling. On the planting ground a banking with a height of 1.5-2m is produced by self-supported soil, playing a role in a salt blocking and an irritation layer of planting. Finally, an additional banking with a height of 2m is produced by qualified vegetation soil, forming a vegetation section with a total height of 6m. 2. Since the planning site is located in the border, the planting area is composed of two regions : one is an inclined face (slope 1 : 3) toward the inside of the landfill site and the other is an inclined face (slope 1 : 4) toward the inland. The buffer planting in the former (latter) region consists of wind break forest (mixed-landscape forest) within a width of less than 35m. 3. Based on the data obtained from the literatures and the investigation of local plants, we choose the 21 plant species (such as Pinus thunbergii, Pinus densiflora, Sorbus alnifolia, Albizzia julibrissin and etc.) and the additinal 7 species which are grown at a sprout cultivation palce of the SUDOKWON landfill site (Rosa rugosa, Quercus acutissima, Prunus armeniaca var. ansu., and etc.). Sub-trees with a height of above 2.5m and seedlings are planted with an interval of $1.5{\times}1.5m$ ($0.45roots/m^2$) and $0.5{\times}0.5m$ ($4roots/m^2$), respectively. Here, both trees exhibit communities planting with more than three rows. Shrubs are planted with $9-16roots/m^2$, depending on their size. Since this case study provides a reference of the planting beds as well as a planting plan at the SUDOKWON landfill site, it is not sufficient for the present plan to be utilized for the formation of buffer-forest belts which are used for the analysis of environmental factor and the reduction of environmental pollutants in the sea waste landfill site. Thus, further studies with the ecological basis are demanded for the environment planting restoration in the sea waste landfill site.

• 한국지형학회지
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• 제23권1호
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• pp.17-33
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• 2016

Samples from newly exposed outcrop of sedimentary layers forming Jeongdongjin coastal terrace in Gangreung area are collected and analyzed to find the sedimentary environment. The site are located at the gentle hillslope of the terrace surface area. The height of the outcrop is about 8m and the altitude of it's highest part is 68~73m MSL. The lowest part of this out crop is the partly consolidated sand layer with gravel veneer within it. It is found that this part is not in-situ weathered sand stone through the OSL method. This sand layer is overlain by the gravel layer with sand matrix. The shapes of the gravels from this part are mainly 'platy', 'elongated', and 'bladed' by the index of Sneed and Folk(1958). In addition, mean roundness is not so high. It is sceptical to regard this part as marine sediments which are continuously exposed to erosional processes. The boundary between the lowest sand layer and gravel layer showing the abrupt change in forming material without any mixture or transitional zone, so gravels are seemed to deposited after some degree of consolidation of the lowest sand layer. In addition, the hight of the boundary between layers are changed by the place, so the surface of the partly consolidated sand layer is not flat and has irregularity on topography when it buried by gravels. Main part of this out crop is the poorly sorted coarse gravel(22.4mm) with sand matrix($1.36{\phi}$) layer with at least 2m thick covering the relatively fine gravels discussed above. Over 20% of particles have 'very platy', 'very elongated' and 'very bladed' shape and only less than 5% of particles have 'compact' shape, So this particles are also very hard to be regard as marine gravels which are abraded by marine processes. It can be concluded that this gravel layer formed by fluvial processes rather than coastal processes base on the form of the clast and sedimentary structure. The gravel layer is covered by fine($3{\sim}4{\phi}$) material layers of psudo-gleization which showing inter-bedding of red and white layers. Chemical composition of matrix and other fine materials should be analyzed in further studies. It is attempted to fine the burial ages of the sediment using OSL method, but failed by the saturation. So it can be assumed that these sediments have be buried over 120ka.

• 한국전산구조공학회논문집
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• 제27권3호
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• pp.137-145
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• 2014

본 논문에서는 브리징 스케일 분해를 기반으로 멀티스케일 문제에 대한 설계민감도 해석법을 개발하였다. 나노 기술의 급속한 발전으로 인해 나노 수준의 해석의 필요성이 지속적으로 증가하고 있다. 최근 분자동역학과 연속체역학의 연성문제에서 많은 해석 방법들이 개발되었다. 본 논문에서는 연성시스템 해석을 위해 브리징 스케일 기법을 사용한다. 전체 영역의 분자동역학 시스템의 해석은 많은 양의 계산 비용이 들기때문에 분자동역학과 연속체 시뮬레이션의 연성시스템을 선호한다. 분자동역학과 연속체 수준 사이의 정보 교환은 분자동역학과 연속체의 경계에서 일어난다. 브리징 스케일 법에서 일반화된 랑지벵 방정식은 축소된 영역의 분자동역학 시스템 해석을 위하여 요구되고, 시간이력 커널을 사용하여 구한 GLE 힘은 분자동역학 시스템에서 경계에 있는 원자들에 작용한다. 그러므로 분자동역학과 연속체 수준의 시뮬레이션을 분리해서 해석할 수 있으며 계산 과정을 가속시킬 수 있다. 연성문제의 시뮬레이션 이후에는 설계의 최적화를 위해 설계민감도 해석의 필요성이 자연스럽게 나타나며 전체 시스템의 성능은 나노 스케일의 효과를 고려해서 최적화된다. 설계구배 기반 최적화에서 설계민감도가 요구되지만 유한차분법으로 구한 민감도는 문제가 대형화될 때 계산비용의 제한때문에 비실용적이나 해석적 설계민감도는 효율적인 강점을 갖는다. 본 연구에서는 연성된 분자동역학-연속체 멀티스케일 문제에서 해석적 설계민감도를 유도하여 정확성과 향후 최적설계로의 활용 가능성을 확인하였다.

• 한국도로학회논문집
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• 제13권1호
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• pp.21-32
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• 2011

포장의 동결깊이는 30년간의 기온자료를 분석하여 만든 동결지수를 근거로 하여 동상방지층의 두께를 결정한다. 본 연구에서의 현장계측 지역은 동결지수에 따라 동결지수 550~650$^{\circ}C{\cdot}$일, 450~550$^{\circ}C{\cdot}$일, 350~450$^{\circ}C{\cdot}$일로 구분하여 지역을 선정하였고, 각 지역별로 절토부, 절성경계부, 저성토부(2m 이하 성토부) 구간으로 단면을 구분하였다. 각 단면에 동상방지층 유 무를 구분하여 포장층별로 계측기(온도, 함수비)를 설치하고 데이터를 수집하였다. 현장 모니터링 시스템을 통하여 수집된 데이터 분석을 통하여 포장된 도로의 동결깊이를 결정하는데 이용할 수 있다. 연구 결과, 동상방지층이 없을 경우 동결지수 550~650$^{\circ}C{\cdot}$일 지역에서는 대기온도에 따라 겨울철 노상층의 온도가 $0^{\circ}C$ 이하로 나타났고, 동결지수 450~550$^{\circ}C{\cdot}$일 지역에서는 지역별로 상이했으며, 동결지수 350~450$^{\circ}C{\cdot}$일 지역에서는 동상방지층이 없어도 노상층의 온도가 $0^{\circ}C$ 이하로 나타나지 않았다. 또한, 포장 단면별로 동결깊이를 비교한 결과 대기온도에 따라 동결깊이는 절토부가 가장 높았으며, 절성경계부, 저성토부 순으로 단면별 차이가 나타났다.