• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.477-480
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• 2008

터널의 경우 타구조물에 비해 화재빈도가 상대적으로 높지는 않으나, 밀폐된 공간이라는 특성상 5분이내 1000도 이상으로 급격한 온도상승이 발생할 수 있으므로, 화재발생시 대형인명피해 및 화재 후 막대한 보수/보강비용이 파생된다. 이에 본 연구에서는 선진외국의 터널화재 시나리오를 준용하여 화재강도(ISO, MHC, RWS)에 따른 콘크리트 PC패널라이닝의 내부 전열특성 규명하였으며, 열손상 범위를 도출하기 위해서 ITA 기준을 적용하여 평가하였다. 연구결과 ISO화재조건에서는 30mm, MHC에서는 50mm, RWS에서는 100mm의 화재손상범위가 도출되었으며, 폭렬깊이는 RWS에서 30mm가 발생하는 것으로 나타났다. PC패널이 지보재의 역할을 할 경우엔 최소100mm깊이의 콘크리트 화재손상범위에 대한 내화성능확보방안이 적용되어야 하며, 비 지보재일 경우 PC패널라이닝의 두께를 100mm이상 확보하여야 한다.

• Advances in concrete construction
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• 제15권5호
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• pp.333-348
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• 2023

Fast infrastructure development boosts the demand for shotcrete. Despite sand and stone being the most common coarse and fine aggregates for shotcrete, excessive exploration of these materials challenges the ecological environment. This study utilized an industrial solid waste, high-titanium heavy slag, blended with steel fibers to form Wet Shotcrete of Steel Fiber-reinforced High-Titanium Heavy Slag (WSSFHTHS). It investigated its workability, shotcrete performance and mechanical properties under different water-to-cement ratios, fly ash content, superplasticizer dosage, and steel fiber content. The tunnel excavation and support were investigated by conducting finite element numerical simulation analysis and was used in 3 tunnel lining pipes in Zhonggouwan tailing pond. The major findings are as follows: (1) The water-to-cement ratio (w/c ratio) significantly impacted the compressive strength of WSSFHTHS. The highest 28-day compressive strength of 60 MPa was achieved when the w/c ratio was 0.38; (2) Adding fly ash improved the workability and shotcrete performance and strength development of WSSFHTHS. The best anti-permeability performance was achieved when the fly ash constituted 15%, with the lowest permeability coefficient of 4.596 × 10-11 cm/s; (3) The optimum superplasticizer dosage for WSSFHTHS is 0.8%. It provided the best workability and shotcrete performance. Excessive dosage resulted in water bleeding and poor aggregate encapsulation, while insufficient dosage decreased flowability and adversely affected shotcrete performance; (4) The dosage of steel fibers significantly impacted the flexural and tensile strength of WSSFHTHS. When the steel fiber dosage was 45 kg/m³, the 28-day flexural and tensile strengths were 8.95 MPa and 6.15 MPa, respectively; (5) By integrating existing shotcrete techniques, the optimal lining thickness was 80 mm for WSSFHTHS per simulation. The results revealed that after using WSSFHTHS, the displacement of the tunnel surrounding the rock significantly improved, with no cracks or hollows, similar to the simulation results.

• 복식문화연구
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• 제20권4호
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• pp.475-484
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• 2012

The purpose of this study is to help to prevent daily noises by measuring the noise absorption coefficient of the non-woven fabrics and wallpapers which are commonly used in lining and noise absorption coefficient of lining curtain. Seven types of fiber materials for the interior decoration, one non-woven fabric for the wallpaper linings, and two types of textiles for curtain linings are used as the experimental materials in this study. The noise absorption coefficient of the noise absorbents were measured by using impedance tube. And the thermal transmittance were measured by using thermal transmittance tester. The results of this study are as follows; Observing the noise absorption efficiency of each experimental materials, the combination of fiber materials and linings, the noise absorption efficiency of cotton, polyester and silk were similar and for the experimental materials of flax, rayon, acrylic and nylon were resulted the similar noise absorption efficiency. The result of combination of fiber material and black fabric was highest among the combined linings. For the combination of fiber material and non-woven fabric, double layers of non-woven fabric resulted slightly higher noise absorption coefficient result than single layer of non-woven fabric. The thermal transmittance and the sound absorbents of experimental materials were affected by the thickness, density and layer of air of the experimental materials.

• 대한치과교정학회지
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• 제11권2호
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• pp.161-168
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• 1981

This study was undertaken to observe the histologic changes of surrounding maxillary sutures to the widening of midpalatal suture, using two adult dogs, weighing about 10 kg, for experimental, and one for control group. After widening of the midpalatal suture with expansion screw for ten days was performed, and followed by sacrifice of experimental animals. Tissues were excised from 5 surrounding maxillary suture portions such as, internasal, interfrontal, midsagittal, zygomatrco-temporal, and midpalatal sutures. After that, the specimens were fixed and decalcified in $10\%$ formalin sol. and $5\%$ nitric acid. Embedding in paraffin and serial sections at a thickness of 5 micron was done, After Hematoxylin-Eosin staining and light microscopic examination, Following results were obtained: 1. In midpalatal suture area, which showed most prominent histologic change, High degree of fibronlastic and osteoblastic proliferation lining the bony trabeculae with osteoid tissue projection into the fibrous connective tissue were observed. 2. In interfrontal suture area, moderate degree of fibroblastic and osteoblastic proliferation was observed. 3. In internasal suture area, active osteoblastic and osteoclastic proliferation lining the bony trabeculae was observed, and separation of fibrous connective tissue was also observed. 4. In midsagittal and zygomatico-temporal suture areas, no histologic changes can be observed.

• 한국물환경학회지
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• 제20권3호
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• pp.206-214
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• 2004

Residual wall thicknesses, corrosion rates, and residual life of thirty four samples of cast iron pipes(CIPs) and ductile cast iron pipes(DCIPs) collected from water mains of B city were studied to estimate their remaining service life or optimum time of rehabilitation. The internal maximum corrosion depths of samples measured using a dial gauge after shot blasting were twice higher than the external in most cases. Therefore corrosion of water pipes was much more affected by internal water quality than soil. Residual wall thicknesses of DCIPs were higher than those of CIPs. That reason was thought to be that DCIPs have been protected from internal corrosion by lining cement mortar. Residual life calculated by maximum corrosion rate was ranged up to 44 years with 12.40 years average. Since most CIPs were much deteriorated, rehabilitation plan should be established soon in B city. Residual life of DCIP was 33.52 years average. When cement mortar lining is used up by neutralization of DCIPs. DCIP also should be rehabilitated.

• 한국구조물진단유지관리공학회 논문집
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• 제4권2호
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• pp.185-191
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• 2000

The safety problem of aged tunnels has been emphasized. For the effective maintenance, site inspection of tunnel structures and surrounding grounds are required periodically. Also, the determination of safety of tunnels is not a simple problem. So the role experienced engineer in the maintenance is very important and development of an expert system that can perform as the engineers, has been needed. In this study, from the results of numerical analysis in several case, new precision inspection rules which can substitute actual numerical analysis are determined by a commercial program FLAC and regression analysis under various parameters such as material property, lining thickness, overburden and laterial coefficients. They are added to the knowledge base to determine safety of tunnel lining. To verify the expert system, the results are compared with an existing tunnel diagnosis report. It can be concluded that the new rule are well represented the actual numerical analysis under various site conditions. Therefore it is expected that the systematic management for effective maintenance of tunnel structure will be possible.

• Geomechanics and Engineering
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• 제17권2호
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• pp.133-143
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• 2019

An optimal hydraulic section is critical for irrigated water conservancy in seasonal frozen ground due to a large proportion of water leakage, as investigated by in-situ surveys. This is highly correlated with the frost heave of underlain soils in cold season. This paper firstly derived a practical model for frost heave of clayey soils, with temperature dependent thermal indexes incorporating phase change effect. A model test carried out on clay was used to verify the rationality of the model. A novel approach for optimizing the cross-section of irrigation canals in cold regions was suggested with live updated geometry characterized by three unique geometric constraints including slope of canal, ratio of practical flow section to the optimal and lining thickness. Allowable frost heave deformation and tensile stress in canal lining are utilized as standard in computation iterating with geometry updating while the construction cost per unit length is regarded as the eventual target in optimization. A typical section along the Jinghui irrigation canal was selected to be optimized with the above requirements satisfied. Results prove that the optimized hydraulic section exhibits smaller frost heave deformation, lower tensile stress and lower construction cost.

• 한국가축번식학회지
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• 제8권1호
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• pp.46-55
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• 1984

The purpose of the experiment was to clarify morphologically normal growth pattern of the ductus deference in accordance with the sex maturity of meat-type cockerels. 1. Diameter of lumens in u, pp.r, mid and lower parts of ductus deferens, the most conspicuous enlargement of lumen was observed in the lower part. Heights of epithelial layers of ductus deferens showed abrupt growth at 12 weeks of age with subsequent gradual growth in all the part of u, pp.r, mid and lower, and heights of those at 30 weeks were a, pp.oximately 4 times as large in the u, pp.r and mid parts and 5 times as large in the lower part in contrast to those at 4 weeks of age. Thickness of muscular layer of ductus showed gradual growth in contrast with the diameter of lumen and height of epithelial layer, showing 1.3 times as large in the u, pp.r part, 1.6 times in the mid part and 1.9 times in the lower part at 30 weeks of age in contrast to the thickness at 4 weeks of age. 2. Within 10 weeks after hatching, lining cells of ductus deferens were mainly composed of round cells and columnar cells in simple columnar epithelium. During 10th to 20th week, the lining cells were mainly composed of high columnar cells and round cells in pseudostratified epithelium. From 22nd week, the lining cells were composed of pseudostratified columnar cells. Whereas round cells disa, pp.ared gradually. Enlargement of lumen and pooling of sperms in ductus deferens coincided with the maturation of seminiferous tubules. 3. In simple correlation between the values of testis weight and the values from various measurements in the ductus deferens, there was significant correlation coefficient with each other. 4. In the India ink absorption test, India ink granules were not absorbed on the epithelium of the ductus deferens, but the granules reactive to acid phosphatase a, pp.ared in a line on the free border of each parts of the ductus deferens. The granules reactive to alkaline phosphatase were noted on the luminal border of ductus deferens mainly, but weak reaction showed than acid phophatase were a, pp.ared. The granules reactive to PAS were a, pp.ared mostly near on the free border of hte epithelial cells of ductus deferens. 5. Number of sperm, Indes of sperm vitality and MRT in the different parts of ductus deferens were tended to be somewhat dominant in the mid and lower parts than in u, pp.r part, even though not significant in the statistical analysis. Ratio of sperm abnormality was tended to be relatively high in the u, pp.r part too, and in the sperm of abnormality blunted head was less in number significantly in the mid and lower part than in the u, pp.r part.

• 지질공학
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• 제11권2호
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• pp.141-152
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• 2001

영천댐 도수로 터널 중 청송군 현서면 지역의 터널 구간(연장 1,484m)에 대한 터널내 유입량과 수리지질학적 특성간의 관계를 연구하였다. 본 연구에서는 터널내로 유입되는 초기 유입량(라이닝 및 그라우팅 이전의 유입량)과 터널지역의 사암층, 절리빈도, 절리간극 및 간격, 단층, 수리전도도간의 관계를 분석하였다. 그리고 절리빈도와 수리전도도의 관계도 고찰하였다. 본 연구지역에서는 단층폭과 터널내 지하수 유입량의 관련성이 가장 크며, 사암의 두께, 수리전도도, 절리빈도순으로 관련성이 낮아지는 것으로 판단된다.

• 한국터널지하공간학회 논문집
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• 제10권4호
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• pp.329-336
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• 2008

도심지 생활 편의를 위한 효율적인 교통 네트워크가 요구되고 있다. 그러나 과밀한 교통 네트워크는 교통체증은 물론 지반환경에 좋지 않은 영향을 주고 있어 터널 및 지하공간에 대한 효율적인 사용과 개발이 요구된다. 지난 20년간 전세계에서 많은 터널 화재사고가 발생하였으며, 그 결과 인명 및 구조물 피해는 물론 경제적으로 큰 손실을 초래하였다. 산악터널의 경우에는 화재 발생에 따른 터널 라이닝의 손상이 터널 안전성에 큰 영향을 주지는 않을 것이다. 그러나, 쉴드터널, 침매터널, 개착터널의 콘크리트 라이닝은 구조부재로 사용되는 관계로 화재 발생이 터널 붕괴로 이어지는 위험성을 안고 있다. 본 연구의 목적은 새롭게 개발된 시멘트계 내화재료로 피복된 터널 철근 콘크리트 라이닝의 내화성능을 평가하기 위함이다. 콘크리트 라이닝 시편을 대상으로 독일의 RABT 내화곡선(최고온도 $1,200^{\circ}C$), 네델란드의 RWS 내화곡선(최고온도 $1,350^{\circ}C$)을 이용하여 실험을 실시하였으며, 그 결과 RABT 내화곡선 하에서는 30mm의 내화피복만으로도 우수한 내화성능을 확인할 수 있었다.