• 대한토목학회논문집
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• 제35권6호
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• pp.1377-1385
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• 2015

우리나라 경제성장의 핵심 원동력이었던 건설업은 오늘날 환경부하량 배출이 가장 많은 산업으로 류되고 있다. 이에 건설업은 친환경을 실현하고자 많은 노력을 기울였지만 그 효과는 미비한 실정이다. 본 연구는 사업 초기단계에서 친환경 VE가 적용이 가능하면 건설업의 친환경 효과가 클 것이라 판단되기에 발주자의 친환경 VE 의사를 파악 할 수 있는 NIA 모델을 개발 후 시뮬레이션 하였다. 경북북부권 환경에너지 종합타운 조성 민간사업의 제안 보고서를 기반으로 친환경 VE 의사를 묻는 20문항을 시뮬레이션 한 결과 50%의 친환경 의사가 있음을 도출 할 수 있었다. 본 연구의 결과는 친환경 VE 의사를 도출하기 위하여 설문조사를 한 후 NIA를 활용하여 건설 초기단계에서 친환경적인 설계를 위한 의사결정시 판단자료로 제공 될 수 있을 것이다.

• Journal of Welding and Joining
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• 제23권6호
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• pp.99-105
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• 2005

The mixing ratio effect of the GTD-111(base metal) powder and the GNI-3 (Ni-l4Cr-9.5Co-3.5Al-2.5B) powder on TLP(Transient Liquid Phase) bonding phenomena and mechanism was investigated. At the mixing ratio of the base metal powder under $50wt\%$, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid insert metal was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solid phases in the bonded interlayer grew epitaxially from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The number of grain boundaries farmed at the bonded interlayer corresponded with those of base metal. At the mixing ratio above $60wt\%$, the base metal powder melted only at the surface of the powder and the amount of the base metal dissolution was also less at the initial time. Nuclear of solids firmed not only from the base metal near the bonded interlayer but also from the remained base metal powder in the bonded interlayer. Finally, the polycrystal in the bonded interlayer was formed when the isothermal solidification finished. When the isothermal solidification was finished, the contents of the elements in the boned interlayer were approximately equal to those of the base metal. Cr-W borides and Cr-W-Ta-Ti borides formed in the base metal near the bonded interlayer. And these borides decreased with the increasing of holding time.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 추계학술대회
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• pp.231-249
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• 2009

The 'Excellent Quality Competitive Enterprises' selection system began with the government's selection and announcement of 'Top 100 Excellent Quality Competitive Enterprises' in 1997 in accordance with Article 6 of the Quality Management and Safety Control of Industrial Products Act and Article 5 (Selection of excellent quality management enterprises, etc.) of the Act's Enforcement Decree. The content of the research and analysis results is summarized as follows: 1. The participation and confidence of enterprises in the differentiation of the assessment system for the excellent quality competitive enterprises selection system is high: from the initial year to the present, 10% of enterprises have participated in the system for over 10 years and since 2000 participating enterprises have been on a steady rise. 2. The distribution of participating enterprises is not limited to any specific region but is spread nationwide, while the participation scale and business types also are being evenly distributed. 3. From the perspective of management performance, as compared with the average of domestic manufacturing businesses or that of U.S. manufacturing businesses, an analysis found that among management results, the excellent quality competitive enterprises achieved far higher sales growth and operating profit rate on sales, however their own capital ratio and debt to equity ratio appeared to be slightly higher.

• Journal of Plant Biology
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• 제37권3호
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• pp.317-323
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• 1994

The calluses formed on the surface of a quarter-girdled Robinia pseudoacacia stems have been shown to originate from immature xylem cells and preexisting cambial cells. The cellus is not only formed by periclinal and anticlinal divisions of radial cells, but also axial cells. In tangential view, the callus at initial stage showed heterogeneous structure composed of long and short cells and then homogeneous one with short cells. Some cells of homogeneous structure in middle region of callus at early stage is later elongated and others mainly divided in trasverse plane. In the result the homogeneous structure becomes into a heterogeneous one. Subsequently, the long cells in heterogeneous structures elongated further and became fusifrom initials, and the short cells divided transversely became ray initials. The appearence of homogeneous and heterogeneous structure in the callus on debarked stem without organ elongation is almost similar to that of the structure in the procambium of young stem which is elongating extensively. Eventually, the ontogeny of vascular cambium in wound callus resembles that of a young stem grown normally, although the debarked stem does not grow in length but in girth and the young stem elongates activity. These findings mean that the active intrusive growth of short procambial cells occurs during the differentiation of fusiform cambial cells.

• 한국식품저장유통학회지
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• 제8권4호
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• pp.374-378
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• 2001

곶감의 건조 및 저장에 따른 미생물상의 변화를 조사하였다. 곳감의 제조 지역에 따라 건조 초기의 미생물수는 상주시 외곽지역의 곶감이 다소 높았으나 반건시상태가 되는 건조 7 주 후에는 두 지역의 미생물 수의 차이는 없었다. 건조가 진행됨에 일반세균과 초산균은 꾸준히 감소하여 7주 후에는 거의 관찰되지 않았으나 곰팡이와 효모 수는 점차 늘어나는 양상을 보였다. 곶감을 3$0^{\circ}C$$\pm$2, 실온(10~15$^{\circ}C$), 저온(4$^{\circ}C$$\pm$2)에서 7주간 저장한 결과 저온 저장구에서 미생물의 증가가 가장 낮았으며, 저온 저장과 상온 저장의 경우에는 저장 기간이 길어질수록 모든 미생물의 수가 증가하는 경향이었으나, 3$0^{\circ}C$ 저장구의 경우 저장 초기에 비하여 저장 기간이 길어질수록 효모와 초산균은 오히려 감소하였다. 외관의 경우에도 저장온도가 낮을수록 백분의 양은 많아지고 조직이 연화되는 기간도 길어지는 것으로 나타났다.

• 한국전기전자재료학회논문지
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• 제22권1호
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• pp.67-73
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• 2009

The stress-strain behavior and its effects on the crack initiation and growth of ITO film on PET substrate with a sheet resistance of 45 ohms/sq were investigated. Electrical resistance increased gradually at the strain of 0.7% in the elastic to plastic transition region of the stress strain curves. Numerous cracks were observed after 1% strain and the increase of the resistance can be linked to the cracking of ITO thin films. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. The spacing between horizontal cracks (perpendicular to the stress axis) increased with decreasing strain rate, The increase of crack density with decreasing strain rate can be attributed to the higher fraction of the plastic strain to the total strain at a given total strain. As the strain increased over 5% strain, cracks parallel to the stress axis were developed and increased in number with strain, accompanied by drastic increases of resistance.

• Structural Monitoring and Maintenance
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• 제6권2호
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• pp.103-124
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• 2019

Present study concerns the safety evaluation of SefidRud dam's block No. 18 regarding probable crack propagation in the foundation gallery under a MCE record. Accordingly, a 3D finite element model of the block in companion with the reservoir and the foundation is modeled. All the associated thermal and structural parameters are derived via calibration with the records of thermometers and pendulums installed inside the dam body. The origination of the cracks and their whereabouts are determined by primary thermal and static analyses and through a linear dynamic analysis the potential failure zone and their extent and level are studied. The foundation gallery is the most probable zone among the other intensive tensile stress area to compromise the dam stability. Therefore, the nonlinear analysis of this risky region is inevitable. The results depict the permissible expansion of the cracks inside the gallery even under another future earthquake in MCE level. As a consequence, the general dam performance is assessed safe in spite of the seepage flow rate growth from the gallery fractures.

• 대한치과보철학회지
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• 제31권4호
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• pp.482-505
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• 1993

The purpose of this study was to evaluate the fracture characteristics and the effect of resin bonding of laminate porcelain. In order to characterize the indentation-induced crack, Young's moduli and characteristic indentation dimensions were measured. The fatigue life under three point flexure test was measured using the electro-dynamic type fatigue machine, and the crack propagation with thermocycling was investigated on the condition of 15 second dwell time each in $5^{\circ}C\;and\;55^{\circ}C$ bath. The Vickers indentation pattern and the fracture surface were examined by an optical microscope and a scanning electron microscope (SEM). The results obtained were summarized as follows ; 1. Young's moduli(E) of the laminate porcelain and the resin cement used in this experiment were $62.56{\pm}3.79GPa$ and $15.01{\pm}0.12GPa$, respectively. 2. The initial crack size of the laminate porcelain was $69.19{\pm}5.94{\mu}m$ when an indentation load of 9.8N was applied, and the fracture toughness was $1.065{\pm}0.156MPa\;m^{1/2}$. 3. The fatigue life of laminate porcelain showed the constant fracture range at the stress level 27.46-35.30MPa. 4. When a cyclic flexure load was applied, the fatigue life of resin-bonded laminate porcelain was more decreased than that of laminate porcelain. 5. When a thermocycling was conducted, the crack growth rate of resin-bonded laminate porcelain was more increased than that of laminate porcelain. 6. Fracture surface showed the radial crack, the lateral crack, and the macroscopic crack branching region beneath the plastic deformation region when an indentation load of 9.8N was applied.

• Geomechanics and Engineering
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• 제36권2호
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• pp.145-156
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• 2024

The mechanical properties of the concrete-frozen soil interface play a significant role in the stability and service performance of construction projects in cold regions. Current research mainly focuses on the precast concrete-frozen soil interface, with limited consideration for the more realistic cast-in-place concrete-frozen soil interface. The two construction methods result in completely different contact surface morphologies and exhibit significant differences in mechanical properties. Therefore, this study selects silty clay as the research object and conducts direct shear tests on the concrete-frozen soil interface under conditions of initial water content ranging from 12% to 24%, normal stress from 50 kPa to 300 kPa, and freezing temperature of -3℃. The results indicate that (1) both interface shear stress-displacement curves can be divided into three stages: rapid growth of shear stress, softening of shear stress after peak, and residual stability; (2) the peak strength of both interfaces increases initially and then decreases with an increase in water content, while residual strength is relatively less affected by water content; (3) peak strength and residual strength are linearly positively correlated with normal stress, and the strength of ice bonding is less affected by normal stress; (4) the mechanical properties of the cast-in-place concrete-frozen soil interface are significantly better than those of the precast concrete-frozen soil interface. However, when the water content is high, the former's mechanical performance deteriorates much more than the latter, leading to severe strength loss. Therefore, in practical engineering, cast-in-place concrete construction is preferred in cases of higher negative temperatures and lower water content, while precast concrete construction is considered in cases of lower negative temperatures and higher water content. This study provides reference for the construction of frozen soil-structure interface in cold regions and basic data support for improving the stability and service performance of cold region engineering.

• 한국자원식물학회지
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• 제37권4호
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• pp.392-400
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• 2024

본 연구는 꽃향유(Elsholtzia splendens)의 재배지대(평야지, 중산간지)와 유형(노지, 비가림하우스 재배)에 따른 생육 및 개화 특성에 대해 구명하고자 수행하였다. 평야지와 중산간지는 각각 해발고도 12 m, 500 m에 위치한 시험포장을 선정하였으며, 재배지대와 유형별 재배관리는 동일한 방법을 적용하였다. 중산간지에서는 평야지 대비 화뢰 출현기(2~3일), 개화기(9일), 만개기(6~7일)가 빨랐으며, 재배유형 중 노지 재배에서 비가림하우스 재배보다 빠른 편이었다. 초장, 주경, 분지수는 정식 후 59~69일까지 급격히 증가한 후 완만해지는 경향을 보였다. 특히 장마기(6월 20일)부터 영양생장의 증가가 완만해지는 시기(정식 후 59~69일)까지의 일조시간(8시간 미만) 일수는 평야지와 중산간지가 각각 22~29일, 26~35일로 조사되었으며, 해당시기는 영양생장에서 생식생장으로 전환되는 시기인 것으로 추정되었다. 재배지대별 꽃향유의 화서 생장량은 평야지보다 중산간지에서 많은 경향이었고, 생육 특성은 주경, 분지수, 건물률을 제외하고는 통계적인 차이가 없었다. 또한 노지재배 대비 비가림하우스 재배에서 개화량과 생장량이 많은 경향이었다. 결과적으로, 경관 목적의 꽃향유 재배 시 일부 개화량차이는 인정되나 평야지와 중산간지 재배가 모두 가능할 것으로 판단된다. 이와 같은 결과는 꽃향유의 기상특성과 생육간의 관계를 이해하기 위한 기본적인 재배정보를 제공할 수 있을 것이다.