• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.360-373
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• 2017

The BTO-a projects is the types, which has a demand risk among the type of PPP projects in Korea. When demand risk is realized, private investor encounters financial difficulties due to lower revenue than its expectation and the government may also have a problem in stable infrastructure operation. In this regards, the government has applied various risk sharing policies in response to demand risk. However, the amount of government's risk sharing is the government's contingent liabilities as a result of demand uncertainty, and it fails to be quantified by the conventional NPV method of expressing in the text of the concession agreement. The purpose of this study is to estimate the value of investment risk sharing by the government considering the demand risk in the profit sharing system (BTO-a) introduced in 2015 as one of the demand risk sharing policy. The investment risk sharing will take the form of options in finance. Private investors have the right to claim subsidies from the government when their revenue declines, while the government has the obligation to pay subsidies under certain conditions. In this study, we have established a methodology for estimating the value of investment risk sharing by using the Black - Scholes option pricing model and examined the appropriateness of the results through case studies. As a result of the analysis, the value of investment risk sharing is estimated to be 12 billion won, which is about 4% of the investment cost of the private investment. In other words, it can be seen that the government will invest 12 billion won in financial support by sharing the investment risk. The option value when assuming the traffic volume risk as a random variable from the case studies is derived as an average of 12.2 billion won and a standard deviation of 3.67 billion won. As a result of the cumulative distribution, the option value of the 90% probability interval will be determined within the range of 6.9 to 18.8 billion won. The method proposed in this study is expected to help government and private investors understand the better risk analysis and economic value of better for investment risk sharing under the uncertainty of future demand.

• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.261-277
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• 2017

This study defines influencing sections as the part of the road section where passing vehicles are traveling with the lower speed compared to speed limit due to speed humps. The influencing section was divided into 3 parts; influencing section before the speed hump, interval section, and influencing section after the speed hump. This analysis focused on the changes of each part depending on installation types, vehicle types, and daytime or nighttime. For the interval section, especially, the ratio of distance traveled with lower speed than speed limit to interval section is defined as effective influencing section ratio to be analyzed. Vehicle speed profiles were collected with a speed gun to extract influencing section lengths. The survival analysis was applied and estimated survival functions are compared with each other by several statistical tests. As a consequence, the average length of influencing section on the 50m sequential speed humps was 75.3% longer during the deceleration than that of isolated speed hump, and 18.9% during the acceleration. The effective influencing section ratio for the 30m and 50m sequential speed humps had a small difference of 81.0% and 76.0% while the absolute values of the section that passing speed were less than the speed limit were longer on 50m sequential speed humps, each being 24.3m and 38.0m. Using the log rank test, it was evident that sequential speed humps were more effective to increase the length of influencing sections compared to the isolated speed hump. Vehicle type was the strong factor for influencing section length on the isolated speed hump, but daytime or nighttime was not the effective one. This research result can be used for improving the efficiency selecting the installation point of speed humps for road safety and estimating the standard of the distance between sequential speed humps.

• Journal of IKEEE
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• v.18 no.4
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• pp.552-558
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• 2014

This paper suggests how to design a ZigBee-chip-based communication module to remotely measure radiation level. The suggested communication module consists of two control processors for the chip as generally required to configure a ZigBee system, and one chip module to configure a ZigBee RF device. The ZigBee-chip-based communication module for remote radiation measurement consists of a wireless communication controller; sensor and high-voltage generator; charger and power supply circuit; wired communication part; and RF circuit and antenna. The wireless communication controller is to control wireless communication for ZigBee and to measure radiation level remotely. The sensor and high-voltage generator generates 500 V in two consecutive series to amplify and filter pulses of radiation detected by G-M Tube. The charger and power supply circuit part is to charge lithium-ion battery and supply power to one-chip processors. The wired communication part serves as a RS-485/422 interface to enable USB interface and wired remote communication for interfacing with PC and debugging. RF circuit and antenna applies an RLC passive component for chip antenna to configure BALUN and antenna impedance matching circuit, allowing wireless communication. After configuring the ZigBee-chip-based communication module, tests were conducted to measure radiation level remotely: data were successfully transmitted in 10-meter and 100-meter distances, measuring radiation level in a remote condition. The communication module allows an environment where radiation level can be remotely measured in an economically beneficial way as it not only consumes less electricity but also costs less. By securing linearity of a radiation measuring device and by minimizing the device itself, it is possible to set up an environment where radiation can be measured in a reliable manner, and radiation level is monitored real-time.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.855-867
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• 2018

When a weak zone exists ahead of tunnel face, the stress in the adjacent area would increase due to the longitudinal arching effect and the stability of the tunnel is affected. Therefore, it is critical to prepare a countermeasure through the investigation of the frontal weakness zone of the excavated face. Although there are several researches to predict the existence of weak zone ahead of tunnel face, such as geophysical exploration, numerical analysis and tunnel support, lack of studies on the relaxation zone depending on the width or distance from the vulnerable area. In this study, the impact of the weak zone on the formation of the relaxation zone was investigated. For this purpose, a series of laboratory test were carried out varying the width of the weak zone and the separation distance between tunnel face and weak zone. In the model test, sand with a water content of 3.8% was used to form a model ground. The model weak zone was constructed with dry sand curtains. The tunnel face was adjusted to allow a sequential excavation of upper and lower half part. load cells were installed on the bottom of the foundation and the tunnel face and measuring instruments for displacement were installed on the surface of the model ground to measure the vertical stress and surface displacements due to tunnel excavation respectively. The test results show that the width of weak zone did not affect the ground settlement while the ground subsidence drastically increased within 0.25D. The vertical stress and horizontal stress increased from 0.5D or less. In addition, the longitudinal arching effect is likely within the 1.0D zone ahead of the tunnel face, which may reduce the vertical stress in the ground following tunneling direction.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.14-21
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• 2008

Bovine blood, cell, tissue, and organ are used as raw materials for manufacturing biopharmaceuticals, tissue engineered products, and cell therapy. Manufacturing processes for the biologicals using bovine materials have the risk of viral contamination. Therefore viral validation is, essential in ensuring the safety of the products. Bovine herpesvirus type 1 (BHV-1) is the most common bovine pathogen found in bovine blood, cell, tissue, and organ. In order to establish the validation system for the BHV-1 safety of the products, a real-time PCR method was developed for quantitative detection of BHV-1 in raw materials, manufacturing processes, and final products as well as BHV-1 clearance validation. Specific primers for amplification of BHV-1 DNA was selected, and BHV-1 DNA was quantified by use of SYBR Green I. The sensitivity of the assay was calculated to be $2\;TCID_{50}/ml$. The real-time PCR method was validated to be reproducible and very specific to BHV-1. The established real-time PCR assay was successfully applied to the validation of Chinese hamster ovary (CHO) cell artificially infected with BHV-1. BHV-1 DNA could be quantified in CHO cell as well as culture supernatant. Also the real-time PCR assay could detect $10\;TCID_{50}/ml$ of BHV-1 artificially contaminated in bovine collagen. The overall results indicated that this rapid, specific, sensitive, and robust assay can be reliably used for quantitative detection of BHV-1 contamination during the manufacture of biologics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.679-690
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• 2015

The need to remove the cause of traffic accidents by improving the engineering system for a vehicle and the road in order to minimize the accident hazard. This is likely to cause traffic accident continue to take a large and significant social cost and time to improve the reliability and efficiency of this generally poor road, thereby generating a lot of damage to the national traffic accident caused by improper environmental factors. In order to minimize damage from traffic accidents, the cause of accidents must be eliminated through technological improvements of vehicles and road systems. Generally, it is highly probable that traffic accident occurs more often on roads that lack safety measures, and can only be improved with tremendous time and costs. In particular, traffic accidents at intersections are on the rise due to inappropriate environmental factors, and are causing great losses for the nation as a whole. This study aims to present safety countermeasures against the cause of accidents by developing an intersection Traffic safety evaluation model. It will also diagnose vulnerable traffic points through BPA (Back -propagation algorithm) among artificial neural networks recently investigated in the area of artificial intelligence. Furthermore, it aims to pursue a more efficient traffic safety improvement project in terms of operating signalized intersections and establishing traffic safety policies. As a result of conducting this study, the mean square error approximate between the predicted values and actual measured values of traffic accidents derived from the BPA is estimated to be 3.89. It appeared that the BPA appeared to have excellent traffic safety evaluating abilities compared to the multiple regression model. In other words, The BPA can be effectively utilized in diagnosing and practical establishing transportation policy in the safety of actual signalized intersections.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.1
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• pp.115-127
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• 2018

This study aims to propose management strategies of ventilation paths for improving urban thermal environments. For this purpose, Gimhae-si in Gyeongsangnamdo was selected as a study area. We analyzed hot spots and cool spots in Gimhae by using Landsat 8 satellite image data and spatial statistical analysis, and finally derived the vulnerable areas to thermal environment. In addition, the characteristics of ventilation paths including wind direction and wind speed were analyzed by using data of the wind resource map provided by Korea Meteorological Administration. As a result, it was found that a lot of hot spots were similar to those with weak wind such as Jinyoung-eup, Jillye-myeon, Juchon-myeon and the downtown area. Based on the analysis, management strategies of ventilation paths in Gimhye were presented as follows. Jinyoung-eup and Jillye-myeon with hot spot areas and week wind areas have a strong possibility that hot spot areas will be extended and strengthened, because industrial areas are being built. Hence, climate-friendly urban and architectural plans considering ventilation paths is required in these areas. In Juchon-myeon, where industrial complexes and agricultural complexes are located, climate-friendly plans are also required because high-rise apartment complexes and an urban development zone are planned, which may induce worse thermal environment in the future. It is expected that a planning of securing and enlarging ventilation paths will be established for climate-friendly urban management. and further the results will be utilized in urban renewal and environmental planning as well as urban basic plans. In addition, we expect that the results can be applied as basic data for climate change adaptation plan and the evaluation system for climate-friendly urban development of Gimhye.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.689-701
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• 2013

Bacterial growth and corresponding consumption of carbon and phosphorus were examined in which tap water samples containing a very low concentration of free chlorine were supplemented with organic carbon and/or phosphorus. The experiments were performed in a fed-batch mode under a controlled temperature of $20^{\circ}C$. In the phosphorus alone-added water, there was no significant increase in bacterial numbers measured as heterotrophic plate count (HPC) in the bulk water. However, bacterial growth was stimulated by the addition of carbon (e.g., bulk HPC levels increased to $10^3CFU/mL$) and further stimulated by the combined addition of carbon and phosphorus (e.g., bulk HPC to $10^5CFU/mL$). The same effects were observed in biofilm HPC and biomass formed on polyethylene (PE) slide surfaces. In the water where organic carbon and phosphorus were added together, the highest biofilm HPC and biomass (measured as extracellular polymeric substance components) densities were observed which were $7.6{\times}10^5CFU/cm^2$ and $5.3{\mu}g/cm^2$, respectively. In addition to the bacterial growth, additions of organic carbon and/or phosphorus resulted in different bacterial carbon-to-phosphorus (C/P) consumption ratios. Compared to a typical bacterial C/P consumption ratio of 100:1, a higher C/P ratio (590:1) occurred in the carbon alone-added water, while a lower ratio (40:1) in phosphorus alone-added water. Comparative value (80:1) of C/P ratio was also observed in the water where organic carbon and phosphorus were added together. At the given experimental conditions, bacterial growth was deemed to be more sensitive to microbially available organic carbon than phosphorus. The effect of phosphorus addition, which resulted in a lower C/P consumption ratio, seemed to be tightly associated with the presence of microbially available organic carbon. These results suggested that the control of extrinsic carbon influx seemed to be more important to minimize bacterial regrowth in drinking water system, since even low content of phosphorus naturally occurring in drinking water was enough to allow a bacterial growth.

• The Korean Journal of Nuclear Medicine
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• v.32 no.3
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• pp.238-249
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• 1998

Purpose: To localize and compare the neural basis of verbal and visual human working memory, we performed functional activation study using $H_2^{15}O$ PET. Materials and Methods: Repeated $H_2^{15}O$ PET scans with one control and three different activation tasks were performed on six right-handed normal volunteers. Each activation task was composed of 13 match-ing trials. On each trial, four targets, a fixation dot and a probe were presented sequentially and subject's task was to press a response button to indicate whether or not the probe was one of the previous targets. Short meaningful Korean words, simple drawings and monochromic pictures of human faces were used as matching objects for verbal or visual memory. All the images were spatially normalized and the differences between control and activation states were statistically analyzed using SPM96. Results: Statistical analysis of verbal memory activation with short words showed activation in the left Broca's area, promoter cortex, cerebellum and right cingulate gyrus. In verbal memory with simple drawings, activation was shown in the larger regions including where activated with short words and left superior temporal cortex, basal ganglia, thalamus, prefrontal cortex, anterior portion of right superior temporal gyrus and right infero-lateral frontal cortex. On the other hand, the visual memory task activated predominantly right-sided structures, especially inferior frontal cortex, supplementary motor cortex and superior parietal cortex. Conclusion: The results are consistent with the hypothesis of the laterality and dissociation of the verbal and visual working memory from the invasive electrophysiological studies and emphasize the pivotal role of frontal cortex and cingulate gyrus in working memory system.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.105-123
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• 2018

Currently, satellite images act as essential and important data in water resources, environment, and ecology as well as information of geographic information system. In this paper, we will investigate basic characteristics of satellite images, especially application examples in water resources. In recent years, researches on spatial and temporal characteristics of large-scale regions utilizing the advantages of satellite imagery have been actively conducted for fundamental hydrological components such as evapotranspiration, soil moisture and natural disasters such as drought, flood, and heavy snow. Furthermore, it is possible to analyze temporal and spatial characteristics such as vegetation characteristics, plant production, net primary production, turbidity of water bodies, chlorophyll concentration, and water quality by using various image information utilizing various sensor information of satellites. Korea is planning to launch a satellite for water resources and environment in the near future, so various researches are expected to be activated on this field.