• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2004년도 추계학술논문발표회 논문집
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• pp.155-159
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• 2004

• Computers and Concrete
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• 제20권2호
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• pp.185-196
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• 2017

Durability problems initiated from steel corrosion are unseen but critical issues, so that many researches are focused on chloride penetration evaluation. Even if RC (Reinforced Concrete) structures are exposed to normal environment, chloride ingress varies with concrete surface conditions and exposed period. This paper presents an analysis technique for chloride behavior evaluation considering time effect on diffusion and surface conditions assumed as double-layered system. For evaluation of deteriorated surface condition, field investigation was performed for concrete pavement exposed to deicing agent for 18 years. In order to consider enhanced surface concrete, chloride profiles in surface-impregnated concretes exposed to chloride attack for 2 years from previous research were investigated. Through reverse analysis, effectively deteriorated/enhanced depth of surface and the related reduced/enlarged diffusion coefficient in the depth are simulated. The proposed analysis technique was evaluated to handle the chloride behavior more accurately considering changes of chloride ingress within surface layer and decreased diffusion coefficient with time. For the concrete surface exposed to deicing agent, the deteriorated depth and enlarged diffusion coefficient are evaluated to be 12.5~15.0 mm and 200% increasing diffusion coefficient, respectively. The results in concrete containing enhanced cover show 10.0~12.5 mm of impregnated depth and 85% reduction of chloride diffusion in tidal and submerged conditions.

• 대한가정학회지
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• 제17권1호
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• pp.1-9
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• 1979

The damaging effects of hemp and cotton by Aspergillus sp, and penicillum sp, which grow successfully on cotton were studied. The damages were measured after cultivated at $30^{\circ}C$ for 10 days the fabrics with Aspergillus sp,and Penicillum sp, respectically, in various conditions. The effects of cell-free extract produced from fungus were also investigated. The results of obtained could be summeried as follows : 1) Cultivation of fungi on fibre in malt extract agar was better than that in czapeck agar. 2) Tnsile strength of the fabrics was deteriortated most easily in czapeak agar at the rae of 49.8%. 3)Growth of fungi was promoted by starching the fibre but tensile strength was felled -off , however, by starching, propagation of fungi was superior on cotton to on hemp. 4) In case of hemp, propagation of fungi was inferior to in case of cotton but the tensile strength was deteriorated at the rate of 26-33%. 5) In case of starched hemp, the tensile strength was deteriorated Slowly in first 8 days, but after 8 days there was no particular change. There was no particular change of tensile strength by starching in cotton. 6) It seemed that a damage of fibre was accelerated because the fungus grow not only on the surface of fabrics but also the inner of those. 7) By treatment of cell-free produced form fungi, the tensile strength of hemp falled off at the rate of 50-65% in first 24 hours, since then the tensile strength was deteriorated slowly for 4 days, but after incubation for 4 days was not changed. But the tensile strength of cotton by cell-free extracts was not effected.

• 대한한방소아과학회지
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• 제18권1호
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• pp.27-48
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• 2004

Objective: The purpose of this study was to investigate the effect of Hwanggigunjungtang(HGT) on white rats with deteriorated immunity caused by methotrexate. Methods: First, methotrexate was fed to the white rats once a day for 4 days. After the immune responses of the rats are deteriorated, dried extracts of HGT mixed in water was fed to the rats once a day for 14 days. And then we measured the percentage of B-cell and T-cell in peripheral blood, the percentage of CD3+CD4+ T-cell and CD3+CD8+ T-cell of blood sampled from spleen and peripheral region. Results: The percentage of B-cell of peripheral blood was not different statistically. The percentage of T-cell of peripheral blood was increased significantly in HGT group as compared with control group. The percentage of CD3+CD4+ T-cell of peripheral blood was increased significantly in HGT group as compared with control group. The percentage of CD3+CD8+ T-cell of peripheral blood was decreased in HGT group as compared with control group. The percentage of CD3+CD4+ T-cell of spleen was increased significantly in HGT group as compared with control group. The percentage of CD3+CD8+ T-cell of spleen was not different statistically. Conclusion: According to the above results, HGT has an effect of increasing immune responses on white rats with deteriorated immunity caused by methotrexate.

• 한국도로학회논문집
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• 제19권5호
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• pp.33-42
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• 2017

PURPOSES : The purpose of this study is to suggest the construction and quality control method for the re-repair of a deteriorated partial depth repair for sections of Portland cement concrete pavement. METHODS : An experimental construction was conducted to extend the repair width for removing an existing repair section. A removal method was used to ensure early performance for a deteriorated partial depth repair section. Bond strength and split tensile strength were measured at the near vertical interface layer between the existing pavement and repair material. The area was analyzed for various conditions such as the extended repair area and the removing method of the existing repair section. RESULTS : As a result of analysis of bond strength and split tensile strength, the bonding performance of a milling removed section was improved over a cutting and hand breaker removed section. The bond strength was analyzed to increase slightly as the extended repair width for removing the existing repair section increased. The split tensile strength did not show a clear relationship to an increased extended repair width of an existing removed repair section. CONCLUSIONS : The milling removal method should be applied in the removal of existing deteriorated partial depth repair sections. The extended repair width for a re-repair section should be wider than the existing partial depth repair with at least a 75-mm length and width for the bond strength and the split tensile strength.

• 콘크리트학회논문집
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• 제25권5호
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• pp.539-546
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• 2013

1997년 시멘트 산업은 자원 재활용 목적을 위하여 산업폐기물을 시멘트 공장에서 사용하기 시작하였다. 그러나 최근, 산업폐기물의 재활용에 따른 시멘트의 환경유해성이 시멘트 공장주변의 오염과 시멘트 내 중금속 용출로 인하여 문제가 제기되고 있는 실정이다. 특히, 시멘트 내 $C^{6+}$의 존재는 중요한 문제가 되고 있으며, 시멘트 내 $C^{6+}$ 최소화를 위한 연구가 수행되고 있다. 그러나 국내에서는 중금속 용출에 관련된 연구는 대부분 시멘트 관점에서 수행되고 있는 실정이다. 시멘트는 콘크리트 재료로 사용되기 때문에 콘크리트 관점에서의 환경안전성 평가가 필요하다. 따라서 이 논문에서는 가혹한 조건에서 열화된 콘크리트의 중금속 용출평가를 실시하였다. 평가 결과 모든 변수에서 $C^{6+}$는 검출되지 않았다.

• 대한한방내과학회지
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• 제25권4호
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• pp.117-128
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• 2004

Objectives : To examine the effects of Gojineumja on white rats which deteriorated immunity caused by Methotrexate(MTX), first of all, MTX was fed to the rats once a day for 4 day. Methods : After the immune response of the rats are deteriorated, dried extracts of Gojineumja(GJE) mixed in water was fed to the white rats once a day for l4days. The next conclusion was made by examining the rates of B-cells and T-cells of the peripheral blood and the changes in rates of CD4+ T-cells and CD8+ T -cells of the blood sampled from the spleen and peripheral region. Especially the count of CD3+ CD4+ T-cells of the peripheral blood and the count of CD3+ CD4+ T-cells of the spleen the count of CD4+/ CD8+ T-cell of the peripheral blood and the spleen proved the significant effect of increasing immune responses statistically. Results :(1) The following are the summary of the results. (2) The percentage of B lymphocyte of peripheral blood was increased significantly in GJE group as compared with control group. (3) The percentage of CD3+ CD4+ T-cell of peripheral blood was increased significantly in GJE group as compared with control group. (4) The percentage of CD3+ CD8+ T-cell of peripheral blood was not different statistically. (5) The percentage of CD4+/ CD8+ T-cell of peripheral blood was increased significantly in GJE group as compared with control group. (6) The percentage of CD3+ CD4+ T-cell of spleen was increased significantly in GJE group as compared with control group. (7) The percentage of CD3+ CD8+ T-cell was not different statistically. (8) The percentage of CD4+ /CD8+ T-cell was not different statistically. Conclusions : Gojineumja has an effect of increasing immune responses on white rats with deteriorated immunity caused by MTX.

• 한국도로학회논문집
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• 제19권6호
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• pp.97-103
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• 2017

PURPOSES : In this study, the pavement condition of non-mill-and-overlay and mill-and-overlay on deteriorated concrete pavement was compared. In addition, the suitable time to perform the initial overlay was investigated. METHODS : The condition of the pavement sections that were not additionally overlaid on non-mill-and-overlay or mill-and-overlay on deteriorated concrete pavements was investigated according to overlay pavement age. The condition of non-mill-and-overlay and mill-and-overlay sections of expressway route 25, which has more information on overlay history than other routes, was compared according to the number of times of overlay. The relation between the concrete pavement condition just before the overlay and the number of times of overlay was investigated for the non-mill-and-overlay and mill-and-overlay sections for which the first overlay was performed in the same year. RESULTS : The pavement condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections, showing higher Highway Pavement Condition Index(HPCI) regardless of overlay pavement age. The number of reflection crackings of the non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. As a result of observing the cores obtained from the overlay sections, the proportion of the deteriorated non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. The SD measured just before the overlay on the concrete pavement for which additional overlay was not performed was smaller than that for which additional overlay was performed regardless of the milling of the concrete slab surface. The HPCI of the concrete pavement for which overlay was performed just once was higher than that for which overlay was performed more than one time. CONCLUSIONS : Accordingly, it was concluded that the condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections. In addition, the better the condition of concrete pavement just before the initial overlay, the longer the duration of the overlay effect.

• 한국농공학회논문집
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• 제60권1호
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• pp.1-10
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• 2018

This study analyzed pore water pressure, seepage and leakage quantity, height of seepage and critical hydraulic gradient in order to suggest the seepage characteristics of agricultural reservoir embankment considering filter interval. The seepage characteristics of a deteriorated reservoir embankments were conducted according to the horizontal filter intervals range using three- dimensional finite element analysis. The wider the horizontal filter interval, the higher the pore water pressure increased, and the pore water pressure ratio in the center of the core has a greater effect than the base part. The seepage and leakage quantity appeared largely in the two-dimensional analysis conditions (case 1), where the filter was constructed totally in the longitudinal direction of the embankment, the wider the horizontal filter interval was gradually reduced. The reasonable filter intervals to yield efficient seepage characteristics were within 30 m for the pore water pressure of the core and the height of the seepage line. The stability of the filter installation was able to evaluate the stability of the piping by the critical hydraulic gradient method. The deteriorated reservoir with no filters or decreased functionality can significantly reduce the possibility of piping by simply installing a filter on the downstream slope. In the future, the deteriorated reservoir embankment should be checked for the reservoir remodeling because the core and filter functions have been lost or decreased significantly. In the case of a new installation, the seepage characteristic behavior due to the core and filter changes should be applied to the field after obtaining a reasonable horizontal filter interval that satisfies the safety factor by a three-dimensional analysis.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.629-632
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• 2008

노후화 된 콘크리트 구조물의 수명을 연장시키기 위해서는 적절한 재료와 공법을 이용해서 보수보강을 해야 한다. 또한 구조물의 열화 상태를 파악하여 조건에 맞는 보수보강을 하는 것이 중요하다. 이번 연구에서는 국내 보수공사에 주로 사용되는 폴리머 시멘트 모르타르를 현장과 실험실에서의 부착강도를 비교 실험하여 폴리머시멘트 모르타르의 부착강도가 현장의 조건과 실험실의 조건에 따라 어떻게 변화되는지에 대한 실험을 진행하였다. 실험한 결과 실험실에서의 부착강도는 대부분 KS F 4042에서 정하는 기준에 만족하는 결과를 얻었지만 현장에서는 기준에 미치지 못하는 결과를 얻었다. 하지만 현장의 데이터는 주로 바탕체를 물고 떨어진 것을 볼 때 원인이 재료만의 문제는 아닌 것으로 판단된다. 따라서 앞으로의 연구는 바탕체의 조건이 폴리머시멘트 모르타르의 부착강도에 어떠한 영향을 미치는가에 대한 연구를 추가적으로 진행할 예정이다.