• Journal of Korean Society on Water Environment
• /
• v.33 no.2
• /
• pp.187-196
• /
• 2017

To ensure hygienic safety of drinking water in a water storage tank, the concentrations of residual chlorine should be above a certain regulation level. In this study, we conducted model simulations to investigate the effects of temperature on residual chlorine in water storage tank conditions typically used in Seoul. For this, values of model parameters (decomposition rate constant, sorption coefficient, and evaporation mass transfer coefficient) were experimentally determined from laboratory experiments. The model simulations under continuous flow conditions showed that the residual chlorine concentrations were satisfied the water quality standard level (0.1 mg/L) at all the temperature conditions ($5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, $20^{\circ}C$ and $25^{\circ}C$). Meanwhile, when the tanks had a no flow condition (i.e., no tap-water influent due to a sudden shut-down), the concentrations became lower than the regulatory level after certain periods. The findings from this modeling works simulating Seoul's water storage tanks suggested disappearance rate of residual chlorine could be reduced through the tanks design optimization with maintenance of low water temperature, minimization of air flow and volume, suppression of dispersion and the use of wall materials with low sorption ability.

• Journal of the Korean Society of Safety
• /
• v.31 no.1
• /
• pp.54-60
• /
• 2016

The bottom of dikes must be kept impermeable to control hazardous chemicals spilled from storage tanks. Currently, insufficient related chemical control laws lead to a possibility to spread through the bottom. Generally, due to the high cost of installation and periodical maintenance, many businesses prefer to install the bottom with general concrete. But, since the impermeability of concrete is dependent on the kind of materials and chemical reaction, all concrete cannot be considered as impermeable material. Thus, it is necessary to make the installation standards of the dike bottom clear in order to avoid the argument over the impermeability and prevent the chemical accident. This study has suggested the standards of impermeable concrete by conducting 7-day exposure test to crude oil with the pilot dikes. The results have showed that the standards have the better impermeable performance compared with the germany standard, which have been penetrated at the maximum penetration depth of 1.9 cm. This study is expected to contribute to both the risk reduction of penetrating into the bottom and the cost reduction of spending to make the bottom of dikes impermeable.

• Journal of the Korean Institute of Rural Architecture
• /
• v.12 no.2
• /
• pp.101-108
• /
• 2010

In this study, designated as scenic in the heart of Darangyi rice field in village of Garchon architectural status to preserve the rural town of quantitative analysis of the characteristics village of Garchon traditional rural villages to build the basis for landscape management are the goal. Most of the buildings housing the seting village of Garchon flavor appears in the form of the natural terrain accept the wall which is exposed on the outside of the roof, wall materials and colors, such as the town without a regular basis to undermine the image of the landscape and so Darangyi rice field standard set for maintenance of landscapes that are needed. Regional officer of the private property of individuals, but local and national recognition of the shared property, and only when done in this regard the establishment of asset and as a scenic area that has to cherish the history and culture between the people who live where the feedback through the exchange of sensitive areas and to the people who live in it will be an alternative to a variety of ways.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.20 no.1
• /
• pp.23-32
• /
• 2022

Pyroprocessing is a promising technology for managing spent nuclear fuel. The nuclear material accounting of feed material is a challenging issue in safeguarding pyroprocessing facilities. The input material in pyroprocessing is in a solid-state, unlike the solution state in an input accountability tank used in conventional wet-type reprocessing. To reduce the uncertainty of the input material accounting, a double-stage homogenization process is proposed in considering the process throughput, remote controllability, and remote maintenance of an engineering-scale pyroprocessing facility. This study tests two types of mixing equipment in the proposed double-stage homogenization process using surrogate materials. The expected heterogeneity and accounting uncertainty of Pu are calculated based on the surrogate test results. The heterogeneity of Pu was 0.584% obtained from Pressurized Water Reactor (PWR) spent fuel of 59 WGd/tU when the relative standard deviation of the mass ratio, tested from the surrogate powder, is 1%. The uncertainty of the Pu accounting can be lower than 1% when the uncertainty of the spent fuel mass charged into the first mixers is 2%, and the uncertainty of the first sampling mass is 5%.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.34 no.8
• /
• pp.51-58
• /
• 2018

G-SEED has been introduced with the aim of reducing energy use and resources since 2002, as the system of certificating environmental friendliness of buildings to create comfortable environment. This study analyzed the changes of certification standard of G-SEED since the revision in 2016, comparing certification results of office buildings by grade, category and certification items between G-SEED 2013-2 version and revised version of 2016. Also, this study analyzed the average points and their standard deviation of certification items including both deleted items and newly added items and extracted items needed to be reviewed in the future revision. In the revision, G-SEED has been extended its certification system to involve existing buildings and Innovative Design categories newly introduced with revising the certification items and difficulties. In revised version of G-SEED, the certification grade appeared to change its acquisition ratio decreasing Green2 and increasing Green4, during Green1 and Green3 were similar in proportion. The average scores by categories appeared decrease in Energy and Environmental Pollution category and Materials and Resources category, on the other hand, Maintenance category appeared the highest increase in the average score. Otherwise, Land Use and Transportation, Water Circulation, Ecology, Indoor Environment categories appeared similar average scores both version of G-SEED. In addition, the Innovative Design which was newly introduced category, seems to expect gradual gaining high scores according to technology development in future, although its possession has shown lower scores in revised version.

• International Journal of Highway Engineering
• /
• v.17 no.2
• /
• pp.55-62
• /
• 2015

Cracking is an inevitable fact of asphalt concrete pavements and plays a major role in pavement deterioration. Pavement cracking is one of the main factors determining the frequency and method of repair. Cracks can be treated with a number of preventative maintenance actions, including overlay surface treatments such as slurry sealing, crack sealing, or crack filling. Pavement cracks can show up as one or all of the following types: transverse, longitudinal, fatigue, block, reflective, edge, and slippage. Crack sealing is a frequently used pavement maintenance treatment because it significantly extends the pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Because current test methods are mostly empirical and only provide a qualitative measure of the bond strength, they cannot accurately predict the adhesive failure of the sealant. This study introduces a laboratory test aimed at assessing the bonding of hot-poured crack sealant to the walls of pavement cracks. A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the bonding strength of the hot-poured crack sealant as a function of the curing time and temperature. Based on a limited number of test results, the hot-poured crack sealants have very different bonding performances. Therefore, this test method can be proposed as part of a newly developed performance-based standard specification for hot-poured crack sealants for use in the future. PURPOSES : The purpose of this study was to evaluate both the adhesion and failure performance of a crack sealant as a function of its curing time and curing temperature. METHODS: A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the adhesion performance of a crack sealant as a function of the curing time and curing temperature. RESULTS: With changes in the curing time, curing temperature, and sealant type, the bond strengths were found to be significantly different. Also, higher bond strengths were measured at lower temperatures. Different sealant types produced completely different bond strengths and failure behaviors. CONCLUSIONS: The bonding strength of an evaluated crack sealant was shown to differ depending on various factors. Two sealant types, which were composed of different raw materials, were shown to perform differently. The newly proposed test offers the possibility of evaluating and differentiating between different crack sealants. Based on alimited number of test results, this test method can be proposed as part of a newly developed performance-based standard specification for crack sealants or as part of a guideline for the selection of hot-poured crack sealant in the future.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.6
• /
• pp.188-197
• /
• 2010

This paper presents research result to study the change of structural capacity of reinforced concrete beams with various shear reinforcement ratios after damage by fire load. In addition, fundamental data are given in order to predict the strength variation of RC member due to fire damage by evaluating the previous calculation method codified in codes. Nine RC beam specimens were made and exposed to the fire controled by the standard fire curve. And the structural capacity was evaluated through a failure test under simple support condition. Previous code formula, ACI code and Eurocode were reviewed and used for the calculation of the strength of specimens damaged by fire. From the test, RC beam specimens exhibited very brittle failure when it exposed to fire controled by standard fire curve during more than one hour. And this failure pattern tended to be more serious when shear reinforcement ratio decreased or fire loading duration increased. From the evaluation of the calculation process in code, the change of strength due to fire can be properly predicted if the damage of materials is well defined.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.4
• /
• pp.41-49
• /
• 2014

In this study, experimental research was carried out to evaluate the structural performance of the reinforced concrete beam using hybrid retrofitting with two materials (groove and embedding FRP rod, CFRP sheet) in existing reinforced concrete buildings. Seven reinforced concrete beams, retrofitted groove and embedding FRP rod (NER series) and groove and embedding FRP rod with CFRP sheet (NERL series), and standard specimen (NBS) were constructed and tested under monotonic loading. Design parameters of test specimens are the amount of groove and embedding FRP rod and lapping CFRP sheet. Test results showed that the maximum load carrying capacity of specimens with groove and embedding FRP rod and groove and embedding FRP rod with CFRP sheet (NERL series) were increased the by 12~46% and 22~77% respectively in comparison with the standard specimen NBS. Test specimens NER series were failed with the adhesion slip and concrete cover separation. And test specimens NERL series were failed with the adhesion slip due to the confining effect of lapping CFRP sheet.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.6
• /
• pp.147-161
• /
• 2017

Generally, significant amount of reinforcements are used in nuclear power plant structures and it may cause several potential problems during the construction. In particular, it is more difficult to pour concrete into structural member joint area than other areas because of the significant congestion of the joint area due to a lot of hooked bars, embedded materials, and other reinforcements. The purpose of this study is to solve these problems due to the reinforcement congestion by using the high-strength(ASTM A615 Gr.80) headed deformed bars of large-sized diameter(43 mm & 57 mm) in nuclear power plant structures as a alternative of standard hooked bars. In order to use headed deformed bars effectively, It is necessary to find the method how to relax limits on their use while maintaining or improving the anchorage capacity. Therefore, this study will analyze the results of tests planned to evaluate the influence of the restricted variables, such as bar size, yield strength, clear cover thickness.

• Journal of Wetlands Research
• /
• v.26 no.2
• /
• pp.139-146
• /
• 2024

Various injection materials, such as asphalt-based injection materials, urethane-based injection materials, cement- based injection materials, and acrylic-based injection materials, are used for the repair of aged conduits and underground structures with cracks. In this study, research was conducted on an environmentally friendly acrylic- based leak repair material that exhibits good curing properties even in humid conditions and stability in temperature fluctuations. To compare the performance of the improved acrylic leak repair material with the existing acrylate injection material, experiments were conducted using KS standard methods, including underwater length change rate tests, underwater leakage resistance tests, and chemical performance tests. The comparative experiments revealed that the improved acrylic leak repair material showed no changes in shrinkage due to humidity, temperature variations, or chemical reactions compared to the existing acrylate injection material. In the underwater resistance test, the improved acrylic leak repair material did not show any leakage. Additionally, to assess the environmental impact of the improved acrylic leak repair material, acute fish toxicity tests and acute oral toxicity tests were conducted, and the results showed no mortality and no specific concerns with the test specimens. The experimental results led to the conclusion that the improved acrylic leak repair material is considered to be superior in performance, environmentally safe, and harmless to the human body. Based on various experimental results, it is inferred that the improved acrylic leak repair material is suitable for use as a repair material for cracks in manholes and underground structures compared to the existing acrylate repair material. This study aims to propose valuable data for future technological development by evaluating the applicability of acrylic leak repair materials.