• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.569-575
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• 2007

The repair of concrete surfaces does not normally take into account structural tolerance for longer service lift and better capabilities of concrete structures. In particular, the repair of surface spelling completes as mortar is applied, which does not display additional structural performances. The use of crimped wire mesh for better construction and fracture resistance, however, expects to have some reinforcement effects. Particularly, it is also expected that the repair of bottom part in structures built between bridges like irrigation structures results in the increase of flexural resistance. Therefore, this study is intended to perform the repair using crimp wire mesh and examine strength depending on the repair section and depth. For this, a slab with 150 mm in depth, 3,000 mm in length and 600 mm in width and total 8 objects to experiment such as upper part, upper whole, bottom part, bottom whole and crimp wire mesh reinforced are manufactured to perform flexural performance. The results of the analysis show that yield strength and failure load increase as the depth of repair materials in the experiment reinforced with crimp wire mesh get bigger. In the same condition, repair of bottom part is able to increase internal force of bending force. Besides, the results show that partial repair of structures under bending force cannot produce flexural performance. Consequently, the repair method with crimp wire mesh results in the increase of flexural resistance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.249-257
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• 2017

Filtering the data for travel time records obtained from DSRC probes is essential for a better estimation of the link travel time. This study addresses the major deficiency in the performance of TRANSGUIDE in removing anomalous data. This algorithm is unable to handle unstable traffic flow conditions for certain time intervals, where fluctuations are observed. In this regard, this study proposes an algorithm that is capable of overcoming the weaknesses of TRANSGUIDE. If TRANSGUIDE fails to validate sufficient number of observations inside one time interval, another process specifies a new validity range based on the median absolute deviation (MAD), a common statistical approach. The proposed algorithm suggests the parameters, ${\alpha}$ and ${\beta}$, to consider the maximum allowed outlier within a one-time interval to respond to certain traffic flow conditions. The parameter estimation relies on historical data because it needs to be updated frequently. To test the proposed algorithm, the DSRC probe travel time data were collected from a multilane highway road section. Calibration of the model was performed by statistical data analysis through using cumulative relative frequency. The qualitative evaluation shows satisfactory performance. The proposed model overcomes the deficiency associated with the rapid change in travel time.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.19 no.2
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• pp.130-145
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• 2006

Objectives : The aim of this work is the approaching of properties-flavours theory and the making of morphological standard in Artemisiae herba. Methods : The properties-flavours theory were attempted with bibliographic method and various climate-information. The external-internal morphological standards were determined by using stereoscope and butanol series. Conclusions : The following is a list the conclusion of the approaching of properties-flavours theory and how to make the standard of morphological standard in artemisiae herba. 1. The significant analysis for the artemisiae herba as the properties-flavours theory, is a follow-up survey of the effect written in the official oriental medicine book 2. The other analytic methods according to the gathering time, processing or storing system or especially nature or growth environment(altitude, temperature,. the mean moisture, and the agronomical survey) by way of the explanation of properties-flavours theory appears so many insufficiency at the many cases. 3. In the case of artemisiae herba., there are 2 cases(Artemisia capillaris $T_{HUNB}$ and A. iwayomogi $K_{ITAMURA}$) in current and recently A. aruwa L. is substituted for artemisiae herba in circulation. 4. The external and internal characteristics according to the shape of original plant or herbal states, entirely correspond to all the official oriental medicine boo 5. According to the place of productiot the difference appeals. (1) A. capillatis $T_{HUNB}$. has leaves like a fine thread, and A. iwayomogi $K_{ITAMURA}$ has big and wide leaves, and shows some reddish color, and A. aruwa L. has narrow leaves, its section lines long vertically. (2) In the internal shapes, as the A. capillatis $T_{HUNB}$. leaves', upper epidermal cell wall shows relatively straight form, its all upper- lower epidemical cell wall has a stoma, and calcium rosette crystal is relatively few. As iwayomogi $K_{ITAMURA}$, all upper- lower epidermal cell wall is wavelike concave, and hypodermics has many stoma and many calcium rosette crystal. (3) In the internal shapes of A. aruwa L. the shape of leaves' epidermal cell is irregular and has so many non-glandular hair nad glandular hair on its surface.

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.479-483
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• 2002

Silicon dioxide thick film using silica optical waveguide cladding was fabricated by Plasma Enhanced Chemical Vapor Deposition(PECVD) method, at a low temperature ($320^{\circ}$C) and from $(SiH_4+N_2O)$ gas mixtures. The effects of deposition parameters on properties of $SiO_2$ thick films were investigated by variation of $N_2O/SiH_4$ flow ratio and RF power. After the deposition process, the samples were annealed in a furnace at $1150^{\circ}$C, in N2 atmosphere, for 2h. As the $N_2O/SiH_4$ flow ratio increased, deposition rate decreased from 9.4 to 2.9 ${\mu}m/h$. As the RF power increased, deposition rate increased from 4.7 to 6.9 ${\mu}m/h$. The thickness and the refractive index measurements were measured by prism coupler. X-ray Photoelectron Spectroscopy(XPS) and Fourier Transform-infrared Spectroscopy(FT-IR) were used to determine the chemical states. The cross-section of films was observed by Scanning Electron Microscopy(SEM).

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.39-47
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• 2003

Rockbursts are mainly caused by a sudden release or the stored strain energy in the rock mass. They have been the major hazard in deep hard rock mines but rarely occur in tunnels. Due to the short history and limited information on rockbursts, the topic has rarely been studied in Korea. Some cases of rockbursts, however, have been reported during construction of a mountain tunnel for waterway. This study focuses on analyzing data on rockbursts obtained from a TBM (Tunnel Boring Machine) tunnel and suggests methods for a comprehensive understanding on rockbursts. From the analysis of the field data of rockbursts, it was found that most rockbursts mainly occurred at the section between the tunnel face and the TBM operating room, and the rock bursting phenomena lasted up to 20 days after excavation in certain areas. The data also show that the bursting spots are located all around the tunnel surface including the face, the wall, and the roof, The maximum size of bursting spots is usually less than 100cm. This study also suggests new scale systems of brittleness and uniaxial compressive strength to evaluate the possible tendency for a rockburst. These systems are scaled based on the scale system of strain energy density. In addition, with these scale systems, this research shows that there are potentially higher tendencies for rockbursts in this specific tunnel. Moreover this research suggests that properties of rock and rock mass, RMR (Rock Mass Rating) value, tunneling method, excavating speed, and depth of tunnel have a strong correlation with rockbursts.

• Toxicological Research
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• v.26 no.4
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• pp.275-283
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• 2010

Placenta transfer study in non-human primate (NHP) is one of the crucial components in the assessment of developmental toxicity because of the similarity between NHP and humans. To establish the method to determine placenta transfer in non-human primate, toxicokinetics of valproic acid (VPA), a drug used to treat epilepsy in pregnant women, were determined in pregnant cynomolgus monkeys. After mating, pregnancy-proven females were daily administered with VPA at dose levels of 0, 20, 60 and 180 mg/kg by oral route during the organogenesis period from gestation day (GD) 20 to 50. Concentrations of VPA and its metabolite, 4-ene-VPA, in maternal plasma on GDs 20 and 50, and concentrations of VPA and 4-ene-VPA in placenta, amniotic fluid and fetus on GD 50 were analyzed using LC/MS/MS. Following single oral administration of VPA to pregnant monkeys, concentrations of VPA and 4-ene-VPA were generally quantifiable in the plasma from all treatment groups up to 4-24 hours post-dose, demonstrating that VPA was absorbed and the monkeys were systemically exposed to VPA and 4-ene-VPA. After repeated administration of VPA to the monkeys, VPA was detected in amniotic fluid, placenta and fetus from all treatment groups, demonstrating that VPA was transferred via placenta and the fetus was exposed to VPA, and the exposures were increased with increasing dose. Concentrations of 4-ene-VPA in amniotic fluid and fetus were below the limit of quantification, but small amount of 4-ene-VPA was detected in placenta. In conclusion, pregnant monkeys were exposed to VPA and 4-ene-VPA after oral administration of VPA at dose levels of 20, 60 and 180 mg/kg during the organogenesis period. VPA was transferred via placenta and the fetus was exposed to VPA with dose-dependent exposure. The metabolite, 4-ene VPA, was not detected in both amniotic fluid and fetus, but small amount of 4-ene-VPA was detected in placenta. These results demonstrated that proper procedures to investigate placenta transfer in NHP, such as mating and diagnosis of pregnancy via examining gestational sac with ultrasonography, collection of amniotic fluid, placenta and fetus after Caesarean section followed by adequate bioanalysis and toxicokinetic analysis, were established in this study using cynomolugus monkeys.

• Journal of Animal Environmental Science
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• v.14 no.1
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• pp.61-68
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• 2008

The roof structural model of liquid manure storage tank was designed to improve a structural safety and an ability of resistance to corrosion by the bad environmental condition with high humidity and high gas concentration. Due to corrosion of a general steel, the 5 years used materials were reduced to one-third of a new material in the result of a bending strength test. Some structural materials were tested to evaluate a strength and an anti-corrosion, and stainless steel pipe (STS439), steel angle with zinc hot dipping, rectangular steel pipe covered with FRP (Fiberglass Reinforced Plastics) resin were selected finally. A stainless steel is more expansive about $3{\sim}5$ times than general structural steel. But its durability under heavy corrosive environment is expected twice as long as general steel. The roof models were designed as closed cone type for each of the three structural materials. In the result of a FEM (Finite Element Method) structural analysis for the developed models, the safe snow depth was higher 2.3 times than a general roof structure, when elements of equal section modulus were used.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.80-97
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• 2010

With the hubbing strategy, construction of "Incheon Airport Railroad(AREX)" was proceeded to expand the accessibility at the level of airports in rivalry like Kansai and Chek Lap Kok. At the present 1st phase which routes from Incheon Airport to Kimpo Airport is opened March 2007. 2nd phase which is planned from Kimpo Airport to Seoul station will be opened at the end of October 2010. But the accessibilty to AREX is delinquent because it is connected only in Seoul station and the maximum operation speed is 110km/h which downgrade the time competitiveness with airport limousine. In addition, transfering of user is necessary to access to AREX from Kyungbu KTX. With these reasons, travel demand in 1st phase section is low(7%). According to reestimation of travel demand, demand analysis result compared with convention condition is insufficient, so required annual average government grant-in-aid amounts to 200 billions won, and it is right time to develop the method for revitalization of Incheon airport railroad. In this paper, facilities plan and operating plan to make new travel demand by speed-up which is able through substitution train now running with high speed train(EMU, 180km/h) and direct connection of KTX, will be suggested. This will contribute to offering high speed railroad service to customers and the reduction of government grant-in-aid by way of demand expansion.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.339-352
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• 2016

The best way of investigating the physical and mechanical properties of subsurface materials is the combined interpretation of data from borehole geophysical surveys and geotechnical experiments with rock samples. In this study two surface seismic surveys with refraction and surface-wave method are alternatively conducted for downhole seismic surveys in test site for geological field trip in Jeungpyung, Chungbuk. P- and S-wave velocity structures are delineated by refraction and MASW (multichannel analysis of shear waves) methods, respectively. Possion's ratio section, reconstructed from P- and S-wave velocities, is correlated to the outcrop geological features consisting of reddish sedimentary rock, gray volcanic rock, and joints/fractures. In addition, rock samples representative for reddish sedimentary and gray volcanic features are geotechnically analyzed to provide physical, mechanical properties, and elastic modulus. Dynamic elastic moduli estimated from geophysical data is found to be higher than the one from geotechnical data. Reddish sedimentary rock characterized with low porosity and moisture content corresponds to the zone of low electrical resistivities and their small variations in the resistivity sections between the rainy and dry days. This trend suggests that the weathered gray volcanic rock and the nearby fractures with higher low porosity and moisture content are interpreted to be good carrier especially in rainy season.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.543-551
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• 2006

Cold-formed steel studs that are being used as load-bearing members of wall panels for steel houses have a problem with their insulation due to the heat bridging of their web. Some additional thermal insulating materials should be used. To solve this problem, the new-concept hybrid stud, which consists of a galvanized steel sheet (t = 1.0 m - 12.0 m) and a GFRP panel (t = 4.0-6.0 mm), has recently been developed. An investigation on the structural behavior and the strength capacity of this new hybrid stud has been conducted so that it can be used in load-bearing wall panels of residential buildings. This paper describes the axial compression-torsion test results of the hybrid studs under both axial compression and torsion using ATTM. The main factors of the test were the stud length, the magnitude of the initial compressive force, and the loading method of the monotonic or cyclic loading. The torsion was applied increasingly while the initial compression was kept constant to the failure of the hybrid section. The advanced analysis results obtained form the finite element procedure that considered the material properties of the high-strength galvanized steel and the GFRP were compared with the test results for verification.