• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.60-67
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• 2018

As the lack of specific aggregation intensifies, the development of alternative resources is urgent. Construction waste is increasing every year, but recycled aggregate is used as a low value added material. Various studies are currently underway at the national level. In this paper, the mechanical performance of the concrete according to the concrete mixing method and the replacement amount of the circulating coarse aggregate was compared and evaluated. Concrete mixing method was normal mixing approach(NMA) method, two-stage mixing approach1 (TSMA1) method, two-stage mixing approach2 (TSMA2) method. Fresh concrete was tested for air content, slump test, and unit volume weight. Compressive strength and flexural strength were tested in hardened concrete. According to the TSMA method, the mechanical performance difference of concrete is shown, and the strength is decreased according to the circulating coarse aggregate replacement amount.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.317-320
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• 2008

These days, the amount of waste concrete has been increasing due to reconstruction and redevelopment. So, the use of recycled aggregates is recommended to solve environmental problems. Some investigations have been carried out to study the flexural behavior of reinforced concrete beams with recycled aggregates. But these have some limitation due to the use of low quality recycled aggregates and small-scale specimens in the laboratory. The purpose of this experimental study is to evaluate flexural behavior of RC beam with recycled fine aggregates. Three RC beams were manufactured with different replacement level of recycled fine aggregates. From the test results, the flexural behavior of the beam is described in terms of crack patterns and failure modes. And the flexural strength of RC beam with different types of recycled fine aggregates is compared with the provision of KCI code.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.661-666
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• 2016

The Internet of Things (IoT) is an infrastructure of physical objects that could be connected to the Internet. Most of these are low performance to ensure a reasonable cost for the smart physical objects. Thus, these devices usually use a lightweight messaging protocol: message queue telemetry transport with SSL/TLS. Cipher suites in device are fixed by default and selected based on preference in SSL/TLS. However, the selected cipher suite provides high security level more than expected. This limitation causes energy waste and overhead of devices. In order to counter this problem, we proposed fuzzy logic based cipher suite decision method to improve energy efficiency. Our proposed method saved 36.03% energy.

• Journal of Korean Physical Therapy Science
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• v.9 no.4
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• pp.63-72
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• 2002

Patient satisfaction is an important factor in evaluating the quality of care. Patient satisfaction may be used to evaluate provider services and facilities, and used to predict the patient returns to a facility. The patients d whether the patient returns to a facility or whether the patient recommends the facility to other people may be affected by a variety of factors of patient satisfaction. Low satisfaction may result in poor compliance with the potential of waste of resources and suboptimal clinical outcome. This study is to identify factors of patient satisfaction that will affect patients decision whether the patient returns or not. A self-administered questionnaire survey was conducted in Seoul, Chung-Joo and Bu-Cheon cities, Survey data was obtained from 743 patients who visited the physical therapy practice at university hospitals, general hospitals and clinics. Response rate was 94.4%. The instrument developed by Goldstein et al. (2000) was used and translated into Korean. Several items were added to the instrument. Patient's opinions of service in each domain measured using 5-point Likert-type scales that ranged from strongly disagree to strongly agree. A multiple-regression analytic approach was used to predict overall satisfaction of physical therapy. Age, kindness, scheduling, convenience of parking, privacy, and waiting time predicted the overall satisfaction of physical therapy. The older patients had higher level of satisfaction with physical therapy compared with the younger patients. Patient satisfaction were more affected by access (scheduling and waiting time), administrative technical management (convenience of parking), and interpersonal management (kindness of physical therapists and other staffs) than clinical technical management (physical therapists' skills).

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.928-935
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• 2010

A bag filter system was partially burnt down during a trial run of waste wood incineration boiler. This brought about unburned hydrocarbon which caused a rapid deactivation of low temperature SCR catalyst set up in two stage after the bag filter. The deactivated catalyst was investigated in order to trace the origin by several characterization methods such as XRD, EDX, BET, TGA, SEM. The deactivated catalyst was regenerated by different methods such as acid washing, water washing in ultrasonication, and calcination treatment under air condition. It is found the calcination treatment under air condition at $450^{\circ}C$ for 2 hours to be the best regeneration method. The catalytic activity was measured in the form of 2 cm ${\times}$ 2 cm ${\times}$ 10 cm (catalyst weight 10 g) honeycomb type. A deNOx efficiency of the regenerated catalyst showed 100% at $180^{\circ}C$ which is the same level of fresh one.

• Animal Bioscience
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• v.34 no.9
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• pp.1479-1490
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• 2021

Objective: Our recent findings confirmed the effectiveness of sodium metabisulfite (SMB) in controlling the growth of undesirable microorganisms in fruit and vegetable discards (FVD); however, lactic acid bacteria (LAB) are susceptible to its antibacterial effects. Two series of experiments were conducted to enable the survivability of LAB during silage fermentation of a total mixed ration (TMR) containing SMB-treated FVD. Methods: In Exp. 1, the objective was to isolate a strain of LAB tolerable to the toxic effect of SMB. In Exp. 2, the SMB load was minimized through its partial replacement with a chemical mixture (CM) based on sodium benzoate (57%), potassium sorbate (29%), and sodium nitrite (14%). FVD was treated with SMB + CM (2 g each/kg biomass) and added to the TMR at varying levels (0%, 10%, or 20%), with or without KU18 inoculation. Results: The KU18 was screened as a presumptive LAB strain showing superior tolerance to SMB in broth medium, and was identified at the molecular level using 16S rRNA gene sequence analysis as Lactobacillus plantarum. Inoculation of KU18 in TMR containing SMB was not successful for the LAB development, biomass acidification, and organoleptic properties of the resultant silage. In Exp. 2, based on the effectiveness and economic considerations, an equal proportion of SMB and CM (2 g each/kg FVD) was selected as the optimal loads for the subsequent silage fermentation experiment. Slight differences were determined in LAB development, biomass acidification, and sensorial characteristics among the experimental silages, suggesting the low toxicity of the preservatives on LAB growth. Conclusion: Although KU18 strain was not able to efficiently develop in silage mass containing SMB-treated FVD, the partial substitution of SMB load with the CM effectively alleviated the toxic effect of SMB and allowed LAB development during the fermentation of SMB + CM-treated FVD in TMR.

• Journal of Climate Change Research
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• v.9 no.1
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• pp.81-90
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• 2018

"The Framework Act on Low-Carbon Green Growth" specifies the requirements for the development and verification of emission factors for establishing reliable national greenhouse gas statistics. The scope of the regulations covers the development and validation of energy, industrial processes, solvents and other product use, agriculture, land use, land use change and emission and absorption coefficients of the forestry and waste sector as defined in the 1996 IPCC Guideline and GPG 2000, The minerals sector to be covered in this study belongs to industrial processes. As a representative method for quantifying and evaluating GHG emission factors, there are emission grade quality grading and DARS (Data Rating Rating System) in the 'Procedures for Preparing Emission Factor Documents (1997)' reported by US-EPA. However, the above two methods are not specific and comprehensive, and lack the details for accurate emission factor verification. Therefore, there is a need for a method for verifying and quantifying certified greenhouse gas emission factors that reflects characteristics of each industry sector in Korea and accord with IPCC G/L and GHG target management. In this study, we conducted a weighted study on quantitative and evaluation lists of emission factor using questionnaires to develop a more accurate methodology for quantifying national greenhouse gas emission factors in the mineral sector. Quantification and evaluation of emission factor are classified into essential verification and quality evaluation. The essential verifications are : administrative compatibility, method of determining emission factors, emission characteristics, sampling methods and analysis methods, representativeness of data. The quality evaluations consisted of the quality control of the data, the accuracy of the measurement and analysis, the level of uncertainty, not directly affect the emission factor, but consisted of factors that determine data quality.

• Progress in Superconductivity and Cryogenics
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• v.21 no.2
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• pp.31-35
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• 2019

Andong-dam was built up in 1967 and it is one of the biggest dams in Korea. Previous studies showed that the sediments are highly contaminated with heavy metals such as arsenic, cadmium, and lead. Many research projects are going on to find out the source of the contamination, to evaluate the toxicities to ecosystem, to estimate the volume of sediment to be treated and to find out a good remediation method. Reports show that the sediment is highly contaminated and the main contamination source is supposed to be abandoned mines and a zinc refinery located upper stream of the river. A magnetic separation has been tested as a treatment method for the dredged sediment. Lab scale test showed that the magnetically captured portion is about 10% in weight but the contamination of heavy metal is much higher than the contamination of the passed portion. This indicates that a magnetic separation could be applied for the purpose of reduction of sediment to be treated and for increasing the volume of low toxic sediments which can be dumped as general waste. A magnetic separation using a HGMS has been tested for the sediment with variable magnetic field and the results showed the higher magnetic field increase the captured portion but the concentrating effect of heavy metal was weakened. Further study is needed to establish a useful technology and optimization between decontamination and reduction of sediment volume.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.17-17
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• 2023

국내의 부지특성 및 감시 관련 규정은 원자력 안전위원회 고시 제2021-16호 제4조(세부지침)와 원자력 안전위원회 고시 제2021-17호 제16조에 의거하고, 국외는 국제원자력기구(IAEA: International Atomic Energy Agency)에서 안전기준을 제시하고 있다(IAEA, 2011). 따라서 국내 중·저준위 방사성폐기물 처분시설은 2006년부터 광역 지질을 포함한 부지 지질/지형, 기상, 수문, 수리지질, 인문사회 등을 망라한 조사를 시행하여 부지 현황에 대한 분석 및 안정성 평가를 수행한다. 부지감시의 수문·지구화학 분야에서는 현장 수질 측정 6항목과 실내 분석 26항목을 감시하고 있으나, 본 연구는 이 중 9개 항목(EC, Na, K, Ca, Mg, SiO₂, Cl, SO₄, HCO₃)을 선정하여 분석하였다. 연구 목적은 물시료 분석자료의 주성분-다중선형회귀-군집 분석과 Piper Diagram 분석결과로부터 해수와 담수(지하수)와의 특성분석 및 해수 영향을 분석하는 것이다. 현장 부지내 지하수 7개 관정(GM-1, 2, 4, 5, 6, 7, 8)과 해수 2개 지점(Sea-1, 2)을 대상으로 통계학적 주성분 분석결과, 대부분의 지하수는2개~4개의 요인으로 구분되고, 해수와의 유사성을 해석하기 위해 확인한 관정은 GM-5, GM-6, GM-1 지점으로 분류되었다. 상기와 같이 해수의 영향을 확인하기 위해 해수 2개 지점과 동일한 군집으로 분류되는 지하수는 GM-5 관정으로 확인되었고, 해안선에서 가까운 GM-5 관정과 같이 유사한 거리에 분포한 지하수 GM-1, 2, 4 관정은 2개 혹은 3개의 최적 군집으로 분류하였을 때도 GM-5와는 다른 특성을 보여주었다. 이는 해안과 인접하더라도 수질은 다른 지질학적 특성(지형, 기상, 단열대 등)에 따라 영향받았음을 지시한다.

• Advances in materials Research
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• v.11 no.2
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• pp.121-146
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• 2022

In the recent years, the use of agricultural waste in green cement mortar and concrete production has attracted considerable attention because of potential saving in the large areas of landfills and potential enhancement on the performance of mortar. In this research, microparticles of palm oil fuel ash (POFA) obtained from a multistage thermal and mechanical treatment processes of raw POFA originating from palm oil mill was utilized as a pozzolanic material to produce high-performance cement mortar (HPCM). POFA was used as a partial replacement material to ordinary Portland cement (OPC) at replacement levels of 0, 5, 10, 15, 20, 25, 30, 35, 40% by volume. Sand with particle size smaller than 300 ㎛ was used to enhance the performance of the HPCM. The HPCM mixes were tested for workability, compressive strength, ultrasonic pulse velocity (UPV), porosity and absorption. The results portray that the incorporation of micro POFA in HPCMs led to a slight reduction in the compressive strength. At 40% replacement level, the compressive strength was 87.4 MPa at 28 days which is suitable for many high strength applications. Although adding POFA to the cement mixtures harmed the absorption and porosity, those properties were very low at 3.4% and 11.5% respectively at a 40% POFA replacement ratio and after 28 days of curing. The HPCM mixtures containing POFA exhibited greater increase in strength and UPV as well as greater reduction in absorption and porosity than the control OPC mortar from 7 to 28 days of curing age, as a result of the pozzolanic reaction of POFA. Micro POFA with finely graded sand resulted in a dense and high strength cement mortar due to the pozzolanic reaction and increased packing effect. Therefore, it is demonstrated that the POFA could be used with high replacement ratios as a pozzolanic material to produce HPCM.