• Elastomers and Composites
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• v.45 no.3
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• pp.199-205
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• 2010

Medium-density fiberboard (MDF) is widely used as an indoor building materials. However, formaldehyde resins, commonly used to bind MDF together, emit formaldehyde and other volatile organic compounds that cause health risk at sufficient concentration. In this study, condensed tannin having formaldehyde absorption ability was used to solve the problem of formaldehyde emission generated from surface material. The synthesis of melamine-formaldehyde resin and reaction of melamine-formaldehyde and condensed tannin were analyzed by FT-IR spectrum. Also surface properties, such as shear force, impact strength, tape adhesion, pencil hardness and gloss retention were measured. Free formaldehyde analysis was performed to analyze remaining unreacted formaldehyde. According to the results, the optimum shear force and impact strength could be obtained by 10 wt.% usage of condensed tannin. In cases of pencil hardness and gloss retention, the optimum properties could be obtained at 20 wt.% of condensed tannin. The amounts of formaldehyde emission of surface material containing 20 wt.% of condensed tannin was 59 ${\mu}g/m^2{\cdot}h$. The amounts of formaldehyde emission could be reduced 3 times by using 20 wt.% of condensed tannin.

• Research in Plant Disease
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• v.14 no.1
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• pp.43-50
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• 2008

Rhizoctonia blight (large patch) caused by Rhizoctonia solani AG2-2 is one of the major diseases on zoysiagrass in golf courses. In this study, anatgonistic bacteria to R. solani AG2-2 were selected in vitro tests using confrontation bioassay and triple layer agar diffusion method. The most active bacteria, Bacillus subtilis CJ-9 were tested for controlling large patch in pots. Relative Performance Indies (RPI) was used as a criterion for the selection of potential biocontrol agent. B. subtilis CJ-9 showed resistance to major synthetic agrochemicals used in golf course. In field tests at golf course, B. subtilis CJ-9 was more effective in suppression of large patch severity and population development of R. solani AG2-2 in soil than chemical fungicides. B. subtilis CJ-9 could be an alternative to chemical fungicides for eco-friendly management of large patch on zoysiagrass.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.800-808
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• 2005

The compounding resin for biodegradable wrap was developed, and its manufacturing process and physical properties were studied. For these purposes, following factors were optimized: the types and amounts of raw resin material, anti-oxidants, and lubricants used. In this work, the stable compounding resin used to make biodegradable wrap was based on poly(butylene adipate-co-butylenesuccinate) (PBAS) and poly(butyleneadipate-co-butylene succinate-co-butyleneterephthalate) (PBAST). The improved properties of resin with an additive were investigated by melting flow index (MFI). From these results, the physical properties of compounding resin, based on PBAST, were more than those of PBAS. For PBAS, the Irganox 1010, 1076 and Irgafos TNPP as the first and second anti-oxidants, respectively, were good. For PBAST, the good first and second anti-oxidants, respectively, were Irganox 1076 and Mark PEP 36. The good lubricants for feeding PBAS and PBAST were glycerol monostearate and palmityl alcohol, respectively. The stability and tensile strength experiment of wrap were also investigated by the elution of heavy metals and universal testing machine (UTM), respectively. The decomposition ratio of developed wrap was increased proportional to the reclaiming time. The degradation ratio of compounding resin sample was about 60% after 40 days.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.4
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• pp.126-133
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• 2017

This study analyzed hydrological changes of stormwater runoff of Seolleung Jeongneung zone according to the application of LID system based on landscape Architectural technology. The results are as follows. First, when flooding occurred in Gwanghwamun in July 27, 2011, the maximum instantaneous rainfall amount was 183 mm/hr recorded at 10:00 on 27th for 10 minutes, and it was confirmed that rainfall intensity more than three times as high as the maximum rainfall of 57.5 mm/hr. Second, it is possible to control peak flow rate in the case of 1,500mm of soil thickness, so that it is possible to improve the vulnerability of flood damage in Seolleung and Jeongneung zone when applying the LID system. Third, in the berm height scenario, peak flow rate control was not controled in all depth level models, but the first stormwater runoff was delayed by 4 hours and 10 minutes compared to the soil thickness scenario. It was interpreted as a relatively important indicator the soil thickness for the initial stromwater runoff reduction and the berm height for the peak runoff. Through this, the systematic adaptation of landscape-friendly ecological factors within the cultural property protection zone could theoretically confirm the effects of flood disaster prevention.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.3
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• pp.307-317
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• 2019

To develop sustainable new natural anti-aging ingredients from Korean native plants, we investigated the cultivation potential of Nymphoides indica using the eco-friendly aquaponics system, and tested the anti-aging effects from N. indica extracts. N. indica could be grown in aquaponics system using floating leaved deep water culture method, and propagated through rhizome propagation. It was confirmed that the nitrate ($80{\mu}g/mL$), potassium ($63.5{\mu}g/mL$) and water temperature ($25^{\circ}C$) greatly affected the cultivation of the N. indica. In addition, synergistic effects were found when two major components (3,7-di-O-methylquercetin-4'-O-${\beta}$-glucoside & sweroside) were present at more than about $5{\mu}g/mL$. The extract had a significant effect on the recovery of skin cells damaged by environmental pollutant such as $benzo[{\alpha}]pyrene$, ammonium nitrate, formaldehyde. It also suppressed $PGE_2$, $TNF-{\alpha}$ and COX-2, and inhibited the production of MMP-1. Taken together, the results suggested that the standardized extracts of N. indica cultivated in the aquaponics has considerable potential as a new cosmetics ingredient with an anti-aging effect.

• Membrane Journal
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• v.30 no.6
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• pp.395-408
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• 2020

Polymer electrolyte membrane fuel cells (PEMFCs) have gained much attention as eco-friendly energy conversion devices without emission of environmental pollutant. Polymer electrolyte membrane (PEM) that can transfer proton from anode to cathode and also prevent fuel cross-over has been regarded as a key component of PEMFCs. Although perfluorinated polymer membranes such as Nafion® were already commercialized in PEMFCs, their high cost and toxic byproduct generated by degradation have still limited the wide spread of PEMFCs. To overcome these issues, development of hydrocarbon based PEMs have been studied. Incorporation of cross-linked structure into the hydrocarbon based PEM system has been reported to fabricate the PEMs showing both high proton conductivity and outstanding physicochemical stability. This study focused on the various cross-linking strategies to the preparation of cross-linked PEMs based on hydrocarbon polymers with ion conducting groups for application in PEMFCs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.139-147
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• 2023

As heavy precipitation rates have increased due to climate change, the risk of landslides has also become greater. Studies in the field of disaster risk assessment predominantly focus on evaluating intrinsic importance represented by the use or role of facilities. This work, however, focused on evaluating risks according to the external conditions of facilities, which were presented via debris flow simulation. A random walk model (RWM) was partially improved and used for the debris flow simulation. The existing RWM algorithm contained the problem of the simulation results being overly concentrated on the maximum slope line. To improve the model, the center cell height was adjusted and the inertia application method was modified. Facility information was collected from a digital topographic map layer. The risk level of each object was evaluated by combining the simulation result and the digital topographic map layer. A risk assessment technique suitable for the polygon and polyline layers was applied, respectively. Finally, by combining the evaluated risk with the attribute table of the layer, a system was prepared that could create a list of objects expected to be damaged, derive various statistics, and express the risk of each facility on a map. In short, we used an easy-to-understand simulation algorithm and proposed a technique to express detailed risk information on a map. This work will aid in the user-friendly development of a debris flow risk assessment system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.547-558
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• 2008

With the advent of super cargo ship due to the explosive increase in the amount of cargo shipped via seas, some mega ports are under construction in South Korea, to accommodate the super cargo ship, and some of them already enter their final phase. To sustain the harbor tranquility, mega ports usually comprise huge vertical type breakwaters which are intrinsically vulnerable to the attack of long waves. In this rationale, we present the chamber type breakwater with a circular curtain wall - Eco-breaker 2, to alleviate the reflection of long waves and numerically investigate the hydraulic characteristics of Eco-breaker 2. As a wave driver, we use the Navier-Stokes eq., the most robust wave driver, using SPH (Smoothed Particle Hydrodynamics) and LES (Large Eddy Simulation). For the verification of numerical results, we also carried out hydraulic model test. It is shown that Eco-breaker 2 can effectively alleviate the reflection of long waves with its inherited large organized eddies encompassing the water chamber and some region off the curtain wall of varying size. It is also shown that the scope and strength of large organized eddies strongly depends on the incident wave period, and the reflection coefficient can be lowered to 0.18 by tuning the size of water chamber such that resident time at the chamber is just short of the half period of incident waves. Based on these results, we present the specification of Eco-breaker 2 to boost its use on the development of water environment friendly harbor worldwide.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.100-103
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• 2023

Recently, development of maritime autonomoust surface ships and eco-friendly ships, production and evaluation research considering various marine environments is needed in the field of optimal routes as the demand for accurate and detailed real-time marine environment prediction information expands. An algorithm that can calculate the optimal route while reducing the risk of the marine environment and uncertainty in energy consumption in smart ships was developed in 2 stages. In the first stage, a profile was created by combining marine environmental information with ship location and status information within the Automatic Ship Identification System(AIS). In the second stage, a model was developed that could define the marine environment energy map using the configured profile results, A regression equation was generated by applying Random Forest among machine learning techniques to reflect about 600,000 data. The Random Forest coefficient of determination (R²) was 0.89, showing very high reliability. The Dijikstra shortest path algorithm was applied to the marine environment prediction at June 1 to 3, 2021, and to calculate the optimal safety route and express it on the map. The route calculated by the random forest regression model was streamlined, and the route was derived considering the state of the marine environment prediction information. The concept of route calculation based on real-time marine environment prediction information in this study is expected to be able to calculate a realistic and safe route that reflects the movement tendency of ships, and to be expanded to a range of economic, safety, and eco-friendliness evaluation models in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.964-970
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• 2023

As part of the International Maritime Organization ef orts to reduce greenhouse gas emissions, the maritime industry is exploring low-carbon fuels such as liquefied natural gas and methanol, as well as zero-carbon fuels such as hydrogen and ammonia, evaluating them as environmentally friendly alternatives. Particularly, ammonia has substantial operational experience as cargo on transport ships, and ammonia ship engines are expected to be available in the second half of 2024, making it relatively accessible for commercial use. However, overcoming the toxicity challenges associated with using ammonia as a fuel is imperative. Detection is possible at levels as low as 5 ppm through olfactory senses, and exposure to concentrations exceeding 300 ppm for more than 30 min can result in irreparable harm. Using the KORA program provided by the Chemical Safety Agency, an assessment of the potential risks arising from leaks during ammonia bunkering was conducted. A 1-min leak could lead to a 5 ppm impact within a radius of approximately 7.5 km, affecting key areas in Busan, a major city. Furthermore, the potentially lethal concentration of 300 ppm could have severe consequences in densely populated areas and schools near the bunkering site. Therefore, given the absence of regulations related to ammonia bunkering, the potential for widespread toxicity from even minor leaks highlights the requirement for the development of legislation. Establishing an integrated system involving local governments, fire departments, and environmental agencies is crucial for addressing the potential impacts and ensuring the safety of ammonia bunkering operations.