• 자원리싸이클링
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• 제26권6호
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• pp.10-19
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• 2017

국내 석탄화력발전소의 습식배연탈황공정에서 탈황용 흡수제로 사용하는 국내산 고품위석회석의 결정구조가 분쇄특성 및 용해특성에 미치는 영향을 연구하였다. 광물학적 결정구조가 다른 제천-단양 지역 석회석 4종을 대상으로 결정구조, 분쇄일지수 및 용해도를 비교한 결과 석회석의 결정크기와 구조에 따라 분쇄일지수 차이가 발생하였으며 분쇄일지수가 상대적으로 낮은 석회석의 용해도가 높은 것으로 나타났다. 이에 따라 석회석의 CaO 함량과 함께 결정구조에 따른 분쇄특성도 중요한 반응인자로 확인되었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2005년도 춘계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.18-19
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• 2005

• 생명과학회지
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• 제29권7호
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• pp.769-773
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• 2019

본 연구에서는 습식 나노화 공정 기술을 적용하여 제조한 식물영양제를 이용하여 사과 잎에 흡수되는 칼슘과 마그네슘의 이동 경로 및 흡수율을 비교 분석하였다. 습식 나노화 공정을 통해 불용성 칼슘과 마그네슘을 나노화 처리한 식물영양제의 성분 함량 및 이동경로를 확인하기 위하여 식물 영양제 살포 후 2주, 4주 및 8주 경과 후 잎자루, 잎몸, 옆면으로 구분하여 SEM, EDS 촬영을 통해 분석하였다. 잎자루는 식물 영양제 살포 후 4주차부터 증가하여 8주차에서는 1,115%까지 증가했으며, 사과 잎몸의 경우 2주차의 미살포구에 비해 살포 후 칼슘과 마그네슘의 함량이 감소하였으나, 4주 이후부터는 증가하였으며, 4주차의 뒷면 증가율이 539%로 가장 높았다. 또한, 잎몸의 옆면은 미살포구에 비해 살포구 모두 칼슘과 마그네슘 함량이 증가하였는데 특히, 4주차에 673% 증가하여 가장 높은 증가율을 보였다. 시간이 경과함에 따라 모든 살포구가 미살포구에 비해 칼슘, 마그네슘 함량이 점점 증가하여 나노화 식물영양제의 불용성 칼슘과 마그네슘 성분이 사과의 잎자루에서 잎몸까지 이동한 것으로 판단된다. 본 연구 결과를 보았을 때 습식 나노 공정 기술을 통해 제조된 식물영양제를 활용하면 사과 이외의 다른 작물 에서도 칼슘과 마그네슘 흡수 효과를 얻을 수 있을 것으로 판단하였다. 또한, 식물영양제 이외에도 천연물이나 바이오산업에도 나노 공정 기술의 적용이 가능할 것으로 기대된다.

• Restorative Dentistry and Endodontics
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• 제25권2호
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• pp.243-253
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• 2000

The purpose of this in vitro study was to evaluate dentin bonding by two different dentin bonding systems(DBS) using acetone based primer or adhesive [All Bond 2(AB2), One Step(OS)] when they were applied by wet or dry bonding technique. Morphology of resin-dentin interface and hybrid layer thickness(HLT) were investigated using Confocal Laser Scanning Microscope(CLSM) and compared to shear bond strength(SBS). 72 extracted sound human molars were randomly divided into 4 groups of 18 teeth each - Group 1.(AW); AB2 by wet bonding. Group 2(AD); AB2 by dry bonding. Group 3.(OW); OS by wet bonding, Group 4.(OD); OS by dry bonding. In 6 teeth of each group, notch-shaped class V cavities(depth 2mm) were prepared on buccal and lingual surface at the cementoenamel juction(12 cavities per group). To obtain color contrast in CLSM observation, bonding resins of each DBS were mixed with rhodamine B and primer of AB2 was mixed with sodium fluorescein. Prepared teeth of each group were treated with AB2, OS, respectively according to the manufacturer's instructions except for dentin surface moisture treatment after acid etching. In group 1 and 3, after acid etching, excess water was removed with wet tissue(Kimwipes), leaving consistently shiny, visibly hydrated dentin surface. In group 2 and 4, dentin surface was dried for 10 seconds at 1 inch distance. The treated teeth were then packed with composite resin(${\AE}$litefil) and light-cured. 12 microscopic samples($60{\sim}80{\mu}m$ thickness) of each group were obtained after longitudinal section and grinding(Exakt cutting and grinding system). Morphological investigation of resin-dentin interface and HLT measurement using CLSM were done. For measurement of SBS, remaining 12 teeth of each group were flattened occlusally to remove all enamel and grinded to 500 grit SiC(Pedemet Specimen Preparation Equipment). After applying DBS on the exposed dentin surface, composite resin was applied in the shape of cylinder, which has 5mm diameter, 1.5mm thickness, and light cured. SBS was measured using Instron with a crosshead speed of 0.5mm/min. It was concluded as follows, 1. HLT of AW(mean: $2.59{\mu}m$) was thicker than any other group, and followed by AD, OW, OD in descending order(mean; 2.37, 2.28, $1.92{\mu}m$). Only OD had statistically significant differences(p<0.05) to AW and AD. 2. There were intimate contact of resin and dentin at the interface in wet bonding groups, but gaps or irregular interfaces were observed in dry bonding groups. 3. The length, diameter, density of resin tags were various even in the same group without significant differences between groups and lots of adhesive lateral branches were observed. 4. There were no statistically significant difference of SBS between AB2 and OS, but SBS of wet bonding groups were significantly higher(p<0.05) than dry bonding groups. 5. There were no consistent relationships between HLT and SBS.

• 한국정밀공학회지
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• 제28권6호
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• pp.701-708
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• 2011

Although Titanium material has superior properties, it belongs to difficult-to-machine materials. The present research applies magnetic abrasive finishing to precision machining of internal-face of titanium pipes, and analyzed & assessed the influence of grinding conditions on magnetic abrasive effects through the removed amount and surface roughness of materials. There was the influence on grinding properties according to change of rotational speed, a total input of mixed powder and an input of grinding liquid, and when the total input, rotational speed and ratio of electrolytic iron versus magnetic abrasives are 8g and 1000rpm, it was most advantageous in aspects of surface roughness and material removal amount, and the grinding liquid remarkably improved the surface roughness and material removal amount only with addition of trace amounts of light oil rather than dry machining conditions. And a result of considering the influence on grinding properties by using an inert gas (Argon gas) for improving grinding properties of the internal-face of titanium pipe, the present research has obtained improvement effects in the removal amount and surface roughness through utilization of an inert gas.

• 펄프종이기술
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• 제47권4호
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• pp.5-12
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• 2015

In recent years, it had focused on the improvement of paper properties by addition of NFC (Nano-fibrillated Cellulose). Although the addition of NFC to wet-end of papermaking process could be suggested as a new solution to improve the strength properties of paper, it was not possible to avoid the bad drainage caused by the added NFC's chocking pores of wet web. Instead of the direct addition to wet-end, spraying of NFC to web in wire-section was tried in this study and evaluated by checking various paper properties including surface smoothness, tensile strength, folding endurance and stiffness. According to the increase of spraying amount of NFC, above mentioned paper properties were enhanced without excessive deterioration of drainage. Compared with direct introduction to wet-end, spraying could be regarded as a more proper method to enhance the surface smoothness and strength properties of paper.

• 한국산업보건학회지
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• 제24권4호
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• pp.462-470
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• 2014

Objectives: The purpose of this study was to evaluate quartz concentrations in airborne respirable dust and particle size-related quartz concentrations. Methods: Respirable dust samples were collected using a 10 mm Dorr-Oliver nylon cyclone equipped with a 37 mm, $5{\mu}m$ pore size PVC filter. Dust samples were collected with a Marple's personal cascade impactor from stone grinding operations in five stone-related business located in the Gyeongsangbuk-do area. Results: The geometric mean of quartz concentration in the respirable dust was $0.170mg/m^3$, and the rate of exceeding the Korean Occupational Exposure Limit(KOEL) was 93.3%. The quartz concentration by particle size shows that it was the highest($0.115mg/m^3$) in stage 5($3.50-6.00{\mu}m$), which corresponds with the size of respirable particle. The smaller the particle sizes were, the higher quartz the content became. The mass fractions of inhalable, thoracic, and respirable dust were 72.1%, 36.0%, and 14.4%. Conclusions: The rate of the quartz concentration in respirable dust from stone grinding operations exceeding the American Conference of Governmental Industrial Hygienists Threshold Limit Values was 100%, which means proper work environmental management is required through regular working environmental measurements. Given that the stone grinding operations had a higher small size dust concentrations, there is a need to reduce respirable dust, such as through wet operation and local exhaust ventilation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.962-967
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• 2003

Recently, environmental pollution has become a serious problem in industry, and many researches have been done in order to preserve the environment. The coolant, which promotes lubrication, cooling and penetration, contains chlorine, sulfur and phosphorus to improve the machining efficiency. These additives, which move around into the air during machining, pollute working. Therefore, many researches on how to reduce the amount of coolant during machining have been carried out. However, to reduce even small amount of coolant causes high temperature of a workpiece and it brings thermal defects. In this study, the experiments of wet & dry grinding using cooling methods (using coolant only, mist and compressed cold air only) are performed to solve the problem of environmental contamination and to get a better surface integrity of a workpiece by comparing surface roughness, roundness and residual stress.

• 한국광물학회지
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• 제20권2호
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• pp.135-145
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• 2007

최근 서브미크론 영역의 초미분쇄는 세라믹, 전자재료 등 새로운 기능성 물질의 개발과 더불어 매우 중요하게 인식되고 있다. 특히, 초미립자에 대한 수요증가에 따라 분쇄기로서 교반볼밀의 중요성도 증가하고 있다. 본 연구에서는 1 mm의 볼을 사용하고 700 rpm의 회전속도로 조작한 교반볼밀을 이용하여 방해석, 납석, 활석 등의 무기분말을 시료로 분쇄실험을 행하였다. 무기분말의 분쇄 시, 분쇄 특성의 정량적인 규명을 위하여, 입자의 크기 및 그 분포특성의 분석을 통해 분쇄산물의 입도분포를 얻음과 동시에 중위경의 변화를 관찰하였다. 방해석의 경우 원시료의 중위경이 $6.49{\mu}m$에서 $0.47{\mu}m$로, 납석의 경우 $3.91{\mu}m$에서 $1.14{\mu}m$까지 입자크기가 크게 작아졌으나, 활석의 경우 $10.30{\mu}m$에서 $6.67{\mu}m$까지만 작아져서 많은 변화를 보이지 않았다. 또한, 분쇄산물의 여러 가지 측정 결과를 토대로 분쇄조작 시 분쇄산물의 특성이 분쇄조건에 따라 분쇄속도에 미치는 영향을 알고자 하였다. 같은 실험 조작 조건에서 선택함수를 관찰한 결과, 방해석과 납석은 비슷한 분쇄거동을 보이는 것을 알 수 있었으나, 본 실험범위 내에서 활석의 분쇄거동은 크게 변화하지 않는 것이 관찰되었다.

• 한국식품조리과학회지
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• 제31권5호
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• pp.544-550
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• 2015

분질미, 연질미 및 경질미 쌀 품종을 건식제분과 습식제분 방법으로 제조한 쌀가루의 bakery 제품 활용도를 알아보기 위해서 제조한 잉글리쉬 머핀의 품질특성을 비교한 결과는 다음과 같다. 각각의 쌀가루로 제조한 잉글리쉬 머핀의 무게는 시료간에 유의한 차이가 없었고, 부피, 부피팽창율 및 비용적은 습식제분 분질미 쌀가루를 이용한 잉글리쉬 머핀에서 가장 높았으며, 건식제분 경질미 쌀가루로 제조한 잉글리쉬 머핀에서 가장 낮았다. 외관과 단면 형태를 살펴본 결과, 습식제분 분질미와 연질미 그리고 건식제분 분질미를 이용한 잉글리쉬 머핀이 가장 좋게 나타났다. 색도 측정 결과, L값은 건식제분 경질미를 이용한 잉글리쉬 머핀이 가장 높았고, b값은 건식제분 분질미를 이용한 잉글리쉬 머핀이 가장 높았다. 경도, 점착성 및 씹힘성은 습식제분 분질미를 이용한 잉글리쉬 머핀에서 가장 낮아 부드러웠고, 건식제분 경질미 쌀가루를 이용한 잉글리쉬 머핀에서 가장 높아 단단하게 나타났다. 관능검사 측정 결과, 색, 향미, 외형, 질감 및 전체적인 기호도는 습식제분 분질미 쌀가루를 이용한 잉글리쉬 머핀이 가장 높게 나타났고, 맛에 대한 기호도는 습식제분 연질미 쌀가루를 이용한 잉글리쉬 머핀이 가장 높게 나타났다.