• Membrane Journal
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• v.30 no.2
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• pp.138-148
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• 2020

The purpose of this study was to identify the cleaning efficiency of fouled multi-bore hollow fiber membranes after purification of contaminated water. The PSf (polysulfone) based hollow fiber membrane manufactured by Pure & B Tech Co., Ltd. Was used in this study. The antifouling characteristics during the water treatment were studied using bovine serum albumin (BSA) as a model compound and the chemical resistance was evaluated after long-term impregnation in sodium hypochlorite (NaOCl) solution and Citric acid to understand the long term stability of the membranes. Water permeability and mechanical strength of the membranes after prolonged chemical exposure was measured to observe the change in mechanical stability and long term performance of the membrane. moreover, the recovery efficiency was also evaluated after chemical enhanced backwashing of a membrane contaminated with bovine serum albumin. The PSf hollow fiber membrane exhibited excellent chemical resistance, and it was confirmed that the efficiency of sodium hypochlorite was high as a result of chemical enhanced backwashing.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.81-92
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• 2011

When we bury the infected poultry into the ground, we have many problems such as the difficulty of making sufficient area for burying, environmental contamination by the leachate, unpleasant ordor. Also, in case of burning the carcass of the infected poultry, there are some problems such as high cost, dust, unpleasant odor, etc. It could cause environmental contamination which many peoples and environmental organization complains about. In this study, we develop a treating system which treats the infected poultry carcass in a environmental method preventing the environment contamination. This system is composed of many processes. The euthanasia system uses rigid vinyl to trap and to do a euthanasia the infected poultry with lethal gas, carbon dioxide. And then, with the tractor attached grappler infected poultry carcass could be put into the carcass treating system. The euthanasia system uses rigid vinyl to trap the infected birds and to confine lethal gas, carbon dioxide. Infected poultry carcass are moved to carcass disposal system by collecting device which is attached at tractor. The carcass treatment system (capacity of disposal : 6.3 $m^3$) is installed on a truck and do one pass work, which is input, crush, stir, sterilize, and discharge treated carcass. 1,000 chickens was killed within 9.7min by $CO_2$ (300L/min) in the tent (10 $m^3$). The collecting device could carry 142 chickens at a time, and the movable carcass treatment system could sterilize 2 tons carcass per hour (at one time). This treatment systems was eco-friendly because it reduced the volume of carcass by 31.9% with no wastewater generation.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.1-12
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• 2019

Batch experiments for the soil washing coupled with the magnetic separation process were performed to remediate the soil contaminated with metal and oil wastes. The soil was seriously contaminated by Zn and TPH (total petroleum hydrocarbon), of which concentrations were 1743.3 mg/kg and 3558.9 mg/kg, respectively, and initial concentrations of Zn, Pb, Cu, and TPH were higher than the 2nd SPWL (soil pollution warning limit: remediation goal). The soil washing with acidic solution was performed to remove heavy metals from the soil, but Pb and Zn concentration of the soil maintained higher than the 2nd SWPL even after the soil washing with acidic solution. The 2nd soil washing was repeated to increase the Pb and Zn removal efficiency and the Zn and Pb removal efficiencies additionally increased by only 8 % and 5 %, respectively, by the 2nd soil washing (> 2nd SPWL). The small particle separation from the soil was conducted to decrease the initial concentration of heavy metals and to increase the washing effectiveness before the soil washing and 4.1 % of the soil were separated as small particles (< 0.075 mm in diameter). The small particle separation lowered down Zn and Pb concentrations of soil to 1256.3 mg/kg (27.9 % decrease) and 325.8 mg/kg (56.3 % decrease). However, the Zn concentration of soil without small particles still was higher than the 2nd SPWL even after the soil washing, suggesting that the additional process is necessary to lower Zn concentration to below the 2nd SPWL after the treatment process. As an alternative process, the magnetic separation process was performed for the soil and 16.4 % of soil mass were removed, because the soil contamination was originated from unreasonable dumping of metal wastes. The Zn and Pb concentrations of soil were lowered down to 637.2 mg/kg (63.4 % decrease) and 139.6 mg/kg (81.5 % decrease) by the magnetic separation, which were much higher than the removal efficiency of the soil washing and the particle separation. The 1st soil washing after the magnetic separation lowered concentration of both TPH and heavy metals to below 2nd SPWL, suggesting that the soil washing conjugated with the magnetic separation can be applied for the heavy metal and TPH contaminated soil including high content of metal wastes.

• Journal of the korean Society of Automotive Engineers
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• v.3 no.3
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• pp.14-23
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• 1981

Engine 윤활은 윤활부분에 발생하는 마찰이나 마모를 감소시키는 것으로 일반적으로 생각하고 있으나 냉각, 방장, 압력의 분산 세척등의 여러가지 작용도 동시에 하는 사명이 부과되는 폭넓은 것으로 되어있다. 1. Engine윤활유의 기능 가. 마모를 줄이고 동력의 손실을 막는다. 나. 금속의 접촉을 맞고 마모를 줄인다. 다. 냉각작용을 한다. 라. 세정작용을 한다. 마. 충격이나 진동을 줄인다. 바. 밀용작용을 한다. 사. 부식방지 작용을 한다. 이상의 그 기본적인 기능에 따라 윤활작용을 생각해 본다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1475-1485
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• 2012

This study was conducted in order to understand nutrition teachers (dietitians)' perceptions of barriers to implementation of HACCP system in school foodservices in Gyeongnam, Korea. Questionnaires were distributed to 350 nutrition teachers (dietitians) from November to December of 2009, and 214 were collected and analyzed. The results of this study were as follows. First, nutrition teachers (dietitians) recognized the following as barriers in implementing the HACCP system: 'the status of facilities and utilities'> 'monitoring'> 'work satisfaction'> 'foodservice employees'> 'cooperation of HACCP team'> 'cooperation of persons concerned besides foodservice employees'> 'understanding the HACCP system'. Second, total working experience was found to be the factor most affecting 'cooperation of HACCP team (p<0.01)', 'cooperation of persons concerned besides foodservice employees (p<0.01)', 'foodservice employees (p<0.05)', and 'work satisfaction (p<0.05)'. Further, 'the status of facilities and utilities' was significantly affected by 'construction/reconstruction of kitchen (p<0.01)', 'division of kitchen area (p<0.01)', 'existence of preliminary preparation room (p<0.01)', and 'existence of dishwashing room (p<0.01)'. Third, dietitians perceived the following concerning hindrance factors of the HACCP system according to CCP stage: 'CCP 1'> 'CCP 3'> 'CCP 2, 'CCP 6'> 'CCP 4'> 'CCP 8'> 'CCP 7'> 'CCP 5'. In conclusion, this study showed that nutrition teachers (dietitians) in the Gyeongnam area recognized 'the status of facilities and utilities' from HACCP areas and 'CCP 1 (menu planning)' from CCP stages as the greatest barriers to implementing the HACCP system in school foodservices. To implement the HACCP system successfully in school foodservices, facilities and utilities should be properly equipped, and menu planning training for nutrition teachers (dietitian) should be conducted.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.649-656
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• 2013

This study was conducted to find out about the implementation status of dental treatment infection control standards of dental hygienists. The subjects of research were the dental hygienists working at dentist offices in Chungnam, Cheonan-si using self-input method from July 25th, 2012 to August 1st 2012. The collected data was analyzed after computerized statistical processing using SPSS 18.0. For hepatitis B vaccination, the results were high with 75.0% of answers being 'yes' or auto-active immunity, but for the latest hepatitis vaccination period showed highest results in '5 years or more ago' with 48.0%. Although 93.0% answered that vaccination was important, the percentage of replies that they had vaccination education was relatively low with 41.0%. For the use of personal protection tools the use of protective goggles was low compared to the use of masks and medical gloves. The percentage of subjects that answered that they always wash their hands before treatment was relatively low with 56.0% compared to 82.0% of subjects that answered that they always washed their hands after treatment. Dental treatment equipment washing before sterilization, use of packing and re-sterilization of tools with damaged packing showed high results for 'yes', but the ratio of subjects that answered 'no' to water line management was low with 39%.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.641-644
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• 2008

This paper investigated the plant and raw material of the ready-mixed concrete company which could supply to the second Lotte World on Pusan. the results were summarized as following. Almost plants were mainly using Twin shaft mixer which was 210m$^3$/hr and horizontal type. There was different the number of admixture silos at each plants, and they were separated by types. The mixtures mainly consisted of the ordinary portland cement, fly ash and blast furnace slag. For favorable quality control, each materials had to carry from same factories, and the monitering standard for quality control should be prepared. The coarse aggregates were used with many different producing districts, so they were only used from Y caused by exclusion of quality difference. The crushed, washed and river sands were generally used as fine aggregates, so the fine aggregates which could be possible to supply stable quality were chosen. This study used Poly Carbonic Acid Admixture which was developed to satisfy maintenance of performance till 2 hours and 10MPa at 15 hours.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.83-92
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• 2006

Recently, interest grew recently on the quality of aggregates following the diminution of primary resources from river and the growing construction demand which exhausted high-quality sand sources around large cities and incited the use of low grade aggregates like shore sand and sea sand that can be supplied in natural state. Especially, the environmental preservation concern and the augmentation of public grievance about the exploitation of sea sand as substitute to river sand are gradually impeding the supply. This situation aggravated by the recent interdiction to extract sea sand which resulted in sand crisis that even led once to the suspension of construction works. The lack of sea sand and river sand increased the exploitation of crushed sand which occupies now nearly 20% of the whole quantity of fine aggregates. And, the use of crushed sand may be expected to grow continuously in the future. This paper described that the properties of crushed sand and the concrete using the crushed sand, the technologies to improve quality of crushed sand and the concrete in order to provide information for the production of high-quality concrete using crushed sand.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.205-213
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• 2007

Strength relationships are presented through experimental data from the concrete strength tests in this study. Various strength tests such as the compressive, flexural, and splitting tensile strength and the modulus of elasticity are included. An experimental work was performed to determine the various strength characteristics for various mix designs. Three different coarse aggregates such as granite, limestone, sandstone were used and included were fine aggregates such as natural sand, washed sand and crushed sand. Also included was cement amount as experimental variable. It was confirmed that each strength value with respect to curing time is to follow a typical strength development curve. With this somewhat reliable test results various strength relationships such as flexural strength-compressive strength, splitting tensile strength-compressive strength, modulus of elasticity-compressive strength, splitting tensile strength-flexural strength were analyzed through statistics. Experimental data were well fitted to the 0.5-power relationship of flexural strength and compressive strength which has been commonly accepted. The splitting tensile strength is expected to be best in the linear relationship from the flexural strength data. Finally splitting tensile strength was found to be proportional to the 0.87 power of the cylindrical compressive strength.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.552-557
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• 2015

Ballast gravel in a railroad field is often polluted by grease and heavy metals. In this paper, the performances of a dry cleaning method for polluted ballast gravel in which pollutants on the gravel surface can be physically removed was extensively studied. A polluted ballast cleaning device able to shoot emery blasting media onto the surface using compressed air was prepared. Polluted ballast gravel was put into this device for cleaning, with the treatment time varied from 1 to 10 min. The cleaning efficiency of the total petroleum hydrocarbons and heavy metals were studied. The total petroleum hydrocarbon removal efficiency was 70-80% for gravels sampled from a locomotive waiting line, while it was 40-60% for gravels sampled from a turnout area. The heavy metal removal efficiency exceeded 90% for copper and lead, while it was 65-80% for nickel and zinc. This system was found to be effective for the remediation of polluted ballast gravels.