• Radiation Oncology Journal
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• v.9 no.1
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• pp.7-15
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• 1991

Pentoxifylline (PENTO) has been known to improve RBC fluidity, and thus improve the flux of RBC through narrow capillaries. Additionally, PENTO also decreases the $O_2$ affinity of hemoglobin by increasing 2,3-DPG levels, thereby increasing the $O_2$ release from RBC. Nicotinamide (NA) has been reported to decrease the number of acutely hypoxic cells in tumors by temporarily increasing tumor blood flow. Therefore, the purpose of this study was to examine whether the combination of PENTO and NA (PENTO+NA) would reduce the radioresistance of the Fsall murine fibrosarcoma by oxygenating the hypoxic cells. We obsewed a significantly enhanced radiation-induced growth delay of the FSaII tumors by PENTO+NA. Thus the enhancement ratio was between 2.5 and 2.8 in growth delay assay. The $TCD_{50}$ of control tumors was about 57 Gy, but that of PENTO+NA treated tumors was about 32Gy. Thus $TCD_{50}$ was modified by a factor of 1.8. We also observed that PENTO+NA exerted no effect on the radiation-induced skin damage after the legs without bearing tumors were exposed to X-irradiation. In order to clarify radiosensitizing effects of PENTO+ NA, changes in tumor blood flow and intratumor pOf were measured using laser Doppler flowmetry and $O_2$ microelectrode methods. The tumor blood flow significantly increased at 10 min. after injection of PENTO+ NA. Furthermore, we also found that PENTO+ NA significantly increased intratumor $pO_2$ from 8 to 19 mmHg. We concluded that PENTO+MA was far more effective than NA alone or PENTO alone. The increase in the response of tumors in vivo to X-irradiation appeared to be due mainly to an increase in the tumor oxygenation. Further studies using various concentrations of PENTO alone and in combination with NA to obtain better sequencing and maximal radiosensitization are warranted.

• Journal of the Korean GEO-environmental Society
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• v.10 no.4
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• pp.15-24
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• 2009

Korea is known to have seasonal frost during winter and the effect of low temperatures and water may cause a weakening of pavements. For that reason, frost protection layers have been constructed in pavements to avoid damage caused by frost action. The practies established in USA and Japan have been adopted as anti-frost design methods in Korea. However, the characteristics of Korean soils are different. Additionally, there is no formulation of a reasonable equation for frost penetration depth and the criterion to identify potentially frost-susceptible soils in present pavement design manuals in Korea. Therefore, adequate pavement design procedures in seasonal frost areas, as well as construction and maintenance practices are required. In this paper, frost penetration depths along national roads in Korea were measured and analyzed over several years. The frost penetration depth was analyzed with respect to the provinces of Korea and sunny/ shaded areas. Additionally, measurement results were compared to the formula of the US Army Corps of Engineers and Ifukube in Japan.

• Korean Journal of Construction Engineering and Management
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• v.17 no.3
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• pp.134-142
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• 2016

Main infrastructures, such as levee, dam, bridge, road, etc., are very important due to not only the means of support for social and industrial activities in normal situation but also the means of protection of life and property during disaster occurrence. In spite of this importance of infrastructures, however, any disaster management systems that actively use these infrastructures are not developed yet. Moreover, infrastructures are not usually included in emergency action plans, thus it occurs second and third impact on communities and industries due to collapsing or damage of infrastructures. Therefore, the authors in this paper analyzed previous research, SWOT, STEEP, and patents and technical journals and conducted a technology need survey ni order to understand the trend of disaster management system as well as suggest main research fields and detail research items. The results of this paper will be a foundation of developing an advanced infrastructure integrated system of maintenance and disaster mitigation and contribute our nation to have an active response system by using infrastructure.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.41-48
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• 2011

Warm-mix asphalt(WMA) technology has been developed to allow asphalt mixtures to be produced and compacted at a significantly lower temperature. The WMA technology was identified as one of means to lower emissions for $CO_2$ and has been spread so quickly in the world. Recently, two innovative WMA additives has been developed to reduce mixing and paving temperatures applied in asphalt paving process in Korea. Since the first public demonstration project in 2008, many WMA projects have successfully been constructed in national highways. In 2010, the WMA field trial was conducted on new national highway construction under Dae-Jeon Regional Construction Management Administration. The two different WMA loose mixtures(WMA and WMA-P) and a HMA mixture were collected at the asphalt plant to evaluate their mechanical performance in the laboratory. The Third-scale Model Mobile Loading Simulator(MMLS3) was adopted to evaluate rutting resistance and moisture damage under different traffic and environmental conditions. In this study, plant-produced WMA mixtures using two WMA additives along with the conventional hot mix asphalt(HMA) mixtures were evaluated with respect to their rutting resistance and moisture susceptibility using MMLS3. Based on the limited laboratory test results, plant-produced WMA mixtures are superior to HMA mixtures in rutting resistance and the moisture susceptibility. The WMA additive was effective for producing and compacting the mixture at $30^{\circ}C$ lower than the temperature for the HMA mixture.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.249-260
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• 2008

Although the accident rate is lower than the road tunnel, fire in railway tunnel can bring large damage of human life. In the high speed railway tunnel, the possibility of the railway-disaster (fire) is growing in consideration of the speedy railway and the tunnel length. For that reason, MLTM (Ministry of Land, Transport and Maritime Affairs) published "Rules about the Safety Standard of Railroad (2005.10.27)" and "The Detailed Safety Standard of Railroad (2006.9.22)". According to those, QRA(Quantitative Risk Analysis) technique is recommended to be applied to railway tunnel design which is longer than 1km for assuring the safety function and estimating the risk. However, it is difficult to perform the disaster prevention design due to lack of the detailed standards about event scenario, fire intensity, incidence rate of accidents etc. Therefore, This paper introduces the case of tunnel design for disaster prevention of the Honam high speed railway including the detailed standards of QRA and reasonable safety facilities.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.111-121
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• 2001

Rockfall protection fences are used for diminishing rockfall damage in roads side slopes. In order to install the fences in effective way, the conditions of rock slopes and total predicted impact energy of fa11ing rock should be considered. However, the fences have been constructed without any consideration for lithology, height and slope angle of rock slope in Korea. In addition, the information about the performance of the protection fences, which should be evaluated by in-situ test or laboratory test in order to check out the practical use in the field, is not available. Therefore, in design manual for the rockfall protection fence, the specific details for the installation of this type of fence are not provided yet. The full sized rockfall in situ test was carried out for the calculation of falling energy of rock and the evaluation of the maximum energy absorbing capacity of fence. For this test, the rock slopes whose heights are about 20 m and dip angle of 65 degree, have been chosen. This is because those geometries are mean height and slope angle of most road cut slopes along Korean national highway. Based on the preliminary simulation procedure, four different sizes of concrete ball (0.7, 1.3, 2.3 and 4.3 ton) were prepared and flour different types of protection fence were constructed. The results of this test provide information about the maximum energy absorbing capacity of the fence, kinetic energy of rockfall and restitution coefficient, and these results can be utilized in the establishment of rockfall fence design and construction manual.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.6
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• pp.87-100
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• 2016

This research was performed for the purpose of providing useful and base data and preservation strategy of growth characteristics of Rhododendron micranthum. From the result of research, wild growth area of Rhododendron micranthum was discovered near steep forest road on 695~901m in altitude above sea level of Baekdu-daegan National Arboretum. Vegetation colony structure of Site I was resulted in Pinus densiflora(tree stratum M.I.P.=45.3%) is dominants, Betula schmidtii(arborescent M.I.P.=9.8%) is second dominant, and Site III resulted in Pinus densiflora(tree stratum M.I.P.=30.5%) is dominants, Betula schmidtii(arborescent M.I.P.=10.3%) is second dominant. Site II resulted in Betula schmidtii(arborescent M.I.P.=30.4%) is dominants and Pinus densiflora tree(tree stratum M.I.P.=8.3%) is second dominants. For herbs, it was researched that the rate of one year herb of chrysanthemum family(10), rice family(3), sedge(2) was higher than near forest area. Among Species diversity index, that of Shannon was in range of 0.7348~1.1090. After comparing this with similar area, this value was relatively low. Dominance analysis result was analyzed that various groups are evenly distributed. Monthly highest average temperature is $23.9^{\circ}$ in Site A and Site B, and monthly lowest average temperature is $-4.5^{\circ}C$ in Site I and $-4.7^{\circ}C$ in Site II. Monthly maximum average humidity is 85.6% in Site I and 83.2% in Site II. Monthly minimum average humidity is 60.9% in Site I and 60.8% in Site II and it showed that these 2 area are located far away but have similar temperature and humidity characteristic and climate environment is similar. It was analyzed that humidity is high with the result of annual average humidity is over 60%. In growth characteristic, it showed that doubt damage of Stephanitis pyrioides, exposure of roots, peeled bark was discovered and supplement on this is urgent.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.3
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• pp.213-225
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• 2004

The number of tunnels are in fact increasing as a part of linear improvement project of general national highway and road enlargement and pavement project. Recently, collapses of portal slope are also occurring considerably, due to local raining from severe rain storm and abnormal weather. Accordingly, it was risen a necessity to efficiently respond to tunnel portal slope damage and maintenance in Korea and oversea nations. This paper is a basic proposal to execute a survey on the current status and state of the tunnel portal slopes that were already installed and are now being operated along general national highways, and also to execute state evaluation for the purpose of managing those effectively. As a research method, domestic tunnels were analyzed in accordance with geometrical shape such as access type, portal form, and tunnel type, etc. via field survey to analyze the types of tunnel portal slopes along national highways. State evaluation classification sheet is presented to divide classes for the danger state of the surveyed portal slopes, and then the related grades are divided. It is mainly aimed at classifying the tunnel portal slope along national highways with using this state evaluation, to use it as basic data so that continuous maintenance can be executed in the future in accordance with danger classes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.225-234
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• 2018

Domestic urban areas are experiencing serious traffic congestion problems due to continuous population growth and increased traffic volume. In order to solve the problem of traffic congestion, the study of great depth underground double deck tunnels using underground space is being actively carried out in the urban areas. The characteristics of great depth underground double deck tunnels are low in cross section, so the spread of fire smoke is expected to spread faster than the road tunnel in case of fire. Therefore, it is necessary to provide a fire smoke delay device which delays the spread of fire smoke when a fire occurs in a tunnels. In the previous study, the diffusion effect was analyzed according to the blocking area when the fire smoke spread delay device was operated through the 3D CFD in the study of preventing the smoke spread in the case of the tunnel fire. A study on fire smoke diffusion delay device using spring elasticity which is excellent in applicability to a tunnel and economical value is studied. In this study, fire smoke spread delay system was developed to fire smoke delay was experimentally analyzed. Fire smoke delay effect of fire smoke delay device appeared. Therefore, it is considered that the can minimize the damage of the victims when installed in the great depth underground double deck tunnels.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.51-59
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• 2011

Tensile stress occurs and random crack develops in concrete pavement slab when it contracts by variation of temperature and humidity. The tensile stress decreases and the random crack is minimized by sawcutting the slab and inducing the crack with regular spacing. The random crack, joint damage, decrease of load transfer efficiency are caused by too wide joint spacing while too narrow joint spacing leads to increase of construction cost and decrease of comfort. A mechanistic-empirical joint spacing design method for the concrete pavement was developed in this study. Structurally and environmentally weakest sections were found among the sections showing good performance, and design strengths were determined by finite element analysis on the sections. The joint width for which the load transfer efficiency is suddenly lowered was determined as allowable joint with referring to existing research results. The maximum joint spacing for which the maximum tensile stress calculated by the finite element analysis did not exceed the design strength were found. And the maximum joint width expected by the maximum joint spacing were compared to the allowable joint width. The new method developed in this study was applied to two zones of Hamyang-Woolsan Expressway being designed. The same joint spacing as a test section constructed by 8.0m of joint spacing wider than usual was calculated by the design method. Very low cracking measured at 6 years after opening of the test section verified the design method developed in this study.