• 한국표면공학회지
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• 제51권5호
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• pp.303-308
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• 2018

Currently hydrofluoric acid (HF) based glass etch method is widely used for anti-glare (AG) surface treatment since it can effectively alleviate the specular reflection problem with relatively low processing cost. However, due to the environmental regulation and safety problem, it is essential to develop alternative technology to replace this method. For this, in this paper, we propose sand blasting based AG surface treatment method for display glass. To characterize the sand blasting process, surface roughness, haze, surface durability, and flatness are considered as process outputs and central composite design (CCD) method and response surface model (RSM) method are applied to model each process output. Models for surface roughness and haze showed 96.44% and 97.24% of R-squared values, respectively and they can be applied to optimize AG surface treatment process for various haze level requirements of display industries.

• 한국기계가공학회지
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• 제8권1호
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• pp.24-30
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• 2009

In this paper, the effect of heat treatment on forgeability is investigated and an improved heat treatment cycle is proposed for the bearing steel, SUJ2. An application example of a bearing inner race cold forging, which has small cracks in the bottom after backward extrusion and piercing, is found from a cold forging industry. The process is evaluated by finite element analysis and several heat treatment cycles are examined in order to propose an improved heat treatment cycle. The effect of heat treatment on material hardness and tool life, dimensional accuracy and forming load is revealed through experiment.

• 한국환경과학회지
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• 제8권1호
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• pp.115-123
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• 1999

수영하수처리장 방류수의 해중방류법과 3차 처리 시설 설치의 비용분석을 한 결과는 다음과 같다. 1) 해안에서 4km 거리와 관경을 2m의 해중방류법을 이용한 수용만의 수질을 개선시키는데 소요되는 해중방류관 건설비용은 383억 원이 소요되는 것으로 산출되었다. 2) 수영하수처리장의 유출수를 해중방류관을 통해서 방류할 경우 방류수심을 32m, Diffuser의 길이를 200m로 할 경우의 초기희석배율은 유속에 따라서 56.4∼399.2으로 계산되었다. 3) 질소를 제거하기 위한 순환법의 경우의 20년 동안의 총 비용은 1,364억 원, 인을 제거하기 위한 응집제 첨가 활성슬러지법은 1,010억 원, 해중방류법은 383억 원으로 해중방류법이 3차 처리시설을 설치하는 비용보다 약 2.6∼3.5배 비용을 적게 소요하는 것으로 산출되었다. 4) 해중방류법을 이용할 경우의 수영만의 수질영향을 예측하기 위해서 물질순환모델을 이용하여 예측한 결과 수영만의 수질이 COD, 용존무기질소(DIN)와 용존무기인(DIP)의 전 항목에서 해역환경 II등급을 만족하는 것으로 예측되었다.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.675-682
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• 2013

The sequential separation process, composed of an oxygen sparging process for separating lanthanides and a zone freezing process for separating Group I and II fission products, was evaluated and tested with a surrogate eutectic waste salt generated from pyroprocessing of used metal nuclear fuel. During the oxygen sparging process, the used lanthanide chlorides (Y, Ce, Pr and Nd) were converted into their sat-insoluble precipitates, over 99.5% at $800^{\circ}C$; however, Group I (Cs) and II (Sr) chlorides were not converted but remained within the eutectic salt bed. In the next process, zone freezing, both precipitation of lanthanide precipitates and concentration of Group I/II elements were preformed. The separation efficiency of Cs and Sr increased with a decrease in the crucible moving speed, and there was little effect of crucible moving speed on the separation efficiency of Cs and Sr in the range of a 3.7 - 4.8 mm/hr. When assuming a 60% eutectic salt reuse rate, over 90% separation efficiency of Cs and Sr is possible, but when increasing the eutectic salt reuse rate to 80%, a separation efficiency of about 82 - 86 % for Cs and Sr was estimated.

• 공업화학
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• 제29권5호
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• pp.613-619
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• 2018

본 연구에서는 유입 슬러지에 다양한 전처리 방법과 고액분리장치를 이용한 유출수의 잉여슬러지를 농축 후 내부반송을 적용하여, 중온혐기-고온호기 혼합 슬러지 처리 공정의 슬러지 소화효율과 메탄가스 생성량에 미치는 영향을 비교 검증하였다. 실험실 규모의 혼합 소화공정장치를 제작하여 서로 다른 유입 슬러지 전처리방법을 적용하여 5단계로 실험을 진행하였다. 1단계에서는 열-알칼리처리 전처리를 하여 슬러지를 공급하였고, 2, 3, 4단계에서는 유출수로부터 농축된 잉여슬러지의 내부반송과 각각 열-알칼리처리, 열처리, 알칼리 처리(7일)를 거친 유입 슬러지를 공급하였다. 마지막 5단계에서는 전처리를 하지 않은 슬러지를 공급하였다. 실험 결과, 1단계에서 4단계까지 진행되는 동안 Volatile Suspended Solid (VSS) 제거율은 유입 슬러지 전처리와 내부반송을 적용하는 경우 크게 증가하였으며, 메탄생성량 또한 2단계에서 슬러지 내부반송과 열-알칼리처리 전처리 적용의 경우 285 mL/L/day까지 크게 증가하였다. 한편, 5단계에서 전처리를 하지 않은 슬러지를 공급하였을 경우 VSS 제거율과 메탄 생성량이 크게 감소하였다. 결론적으로, 유입 슬러지의 열-알칼리처리 전처리와 유출수의 농축 잉여슬러지의 내부반송을 통해 복합 슬러지 처리 공정의 슬러지 제거 효율과 메탄생성량을 크게 증가시킬 수 있었다.

• 대한치과교정학회지
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• 제22권3호
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• pp.647-656
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• 1992

The purpose of this study was to evaluate the elastic memory process in cold worked stainless steel wire and the effect of heat treatment on it. 0.018 inch round and $0.019\times0.025$ inch rectangular wire (ORMCO stainless wire) were used in this study. Each wire type had 4 groups: non-heat treatment group, furnace heat treatment group, electric current heat treatment group, and bending after heat treatment group. Each group was consisted of 10 specimens. With the Jig, each wire was bent into v-shape uniformly, and width of two free ends of each v-shaped wire was measured by caliper (to the point of 0.1 mm correctly) at time interval of offjig, after heat treatment, 1, 2, 3, 4 hours, 1, 2, 3, 4, 5, 6 days, 1, 2, 3, 4 weeks after. The results were as follows: 1. In non-heat treatment group and bending after heat treatment group, elastic memory process was occured $60\%$ within 1 hour, and more than $90\%$ within 1 week. 2. In furnace and electric current heat treatment group, almost all elastic memory process was occured during teat treatment, and then specimen was stabilized dimensionally. 3. Magnitude of deformation by elastic memory was greater in heat treatment group than non heat treatment group and bending after heat treatment group. 4. There was no remarkable difference in deformation pattern between 0.018 inch round wire and $0.019\times0.025$ inch rectangular wire.

• 유기물자원화
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• 제20권3호
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• pp.52-59
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• 2012

처리공정별 연계처리수질을 검토한 결과 생물학적처리만 거친 생물반응조 처리수의 경우 연계부하율이 $COD_{Mn}$의 경우 1.67%(설계수질 기준), 2.59%(운영수질 기준), T-P의 경우 3.69%(설계수질 기준), 7.67%(운영수질 기준)로 다소 높게 나타났으나 하수처리장 운영에 미치는 영향은 거의 없을 것으로 판단된다. 또한, 고도처리공정인 산화부상분리 처리수 및 생물여과 처리수의 경우 연계부하율은 1% 내외로 고도처리설비 설치 시 과대 설비설치의 우려가 있다. 따라서 S하수처리장의 경제성 및 안정적인 운영을 고려할 경우 생물학적처리인 생물반응조를 거친 처리수를 연계하는 것이 바람직할 것으로 판단된다.

• 상하수도학회지
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• 제37권5호
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• pp.253-259
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• 2023

Bioreactors are devices used by sewage treatment plants to process sewage and which produce active sludge, and sediments separated by solid-liquid are treated in anaerobic digestion tanks. In anaerobic digestion tanks, the volume of active sludge deposits is reduced and biogas is produced. After dehydrating the digestive sludge generated after anaerobic digestion, anaerobic digested wastewater, which features a high concentration of organic matters, is generated. In this study, the decomposition of organic carbon and nitrogen was studied by advanced oxidation process. Ozone-microbubble flotation process was used for oxidation pretreatment. During ozonation, the TOC decreased by 11.6%. After ozone treatment, the TOC decreased and the removal rate reached 80.4% as a result of the Ultra Violet-Advanced Oxidation Process (UV-AOP). The results with regard to organic substances before and after treatment differed depending on the organic carbon index, such as CODMn, CODCr, and TOC. Those indexes did not change significantly in ozone treatment, but decreased significantly after the UV-AOP process as the linkage treatment, and were removed by up to 39.1%, 15.2%, and 80.4%, respectively. It was confirmed that biodegradability was improved according to the ratio of CODMn to TOC. As for the nitrogen component, the ammonia nitrogen component showed a level of 3.2×10² mg/L or more, and the content was maintained at 80% even after treatment. Since most of the contaminants are removed from the treated water and its transparency is high, this water can be utilized as a resource that contains high concentrations of nitrogen.

• 환경위생공학
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• 제7권2호
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• pp.37-52
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• 1992

Since the first sewage treatment plant was constructed in 1976, the sewerage systems of Korea have been rapidly expanded. As of the end of 1991, 22 sewage treatment plants with total capacity of 5.4 million tons/day are in operation which is equivalent of 3395 total daily sewage generation. Total extension of sewer 39.534 km in 1990 which is 55% of the target extension for the year 2001. However, the most sewage treatment plants employ activated sludge process which may not be suitable for medium and/or small scale plants. The poor existing sewer systems do not effectively collect and transport sewage to adversely affect the function of sewage treatment plant. To select the appropriate treatment system, the cities are classified into 3 categories such as large and medium size inland cities, small size cities and coastal cities. Considering the criteria suggested during this study, appropriate treatment processes were selected for each category. Conventional activated sludge process and step aeration process were found to be the most appropriate for big inland cities while biological nutrient removal processes should be considered for the cities discharge the effluent to lakes or reservoirs. RBC or Oxidation Ditch process might be appropriate for the medium size cities while several processes which do not require skilled operation and maintenance were suggested for the small cities. Ocean discharge after primary treatment can be considered for some east coast cities, Appropriate methodology to rehabilitate the existing sewers and strategy to convert combined sewer system to separate sewer system were proposed. This paper also include the appropriate management system for industrial wastewater, sludge and nightsoil.

• 상하수도학회지
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• 제35권5호
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• pp.351-365
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• 2021

Water treatment process simulator is the tool for predicting sequential changes of water quality in a train of unit processes. This predicts the changes through governing equations that represent physicochemical performance of each unit processes with an initial and boundary conditions. Since there is no operational data for the design of a water treatment facility, there is no choice but to predict the performance of the facility by assuming initial and boundary conditions in virtual reality. Therefore, a simulator that can be applied in the design stage of a water treatment facility has no choice but to be built as a numerical analysis model of a deductive technique. In this study, we had conducted basic research on governing equations, inter-process data-flow, and simulator algorithms for the development of simulators. Lastly, this study will contribute to design engineering tool development research in the future by establishing the water treatment theory so that it can be programmed in a virtual world and suggesting a method for digital transformation of the water treatment process.