• 통합자연과학논문집
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• 제3권2호
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• pp.112-116
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• 2010

Prepared CdSe nanoparticles were systems, one of the most studied and useful nanostructures. Semiconductor quantum dots (QDs) have been the subject of much interest for both fundamental reseach and technical applications in recent years, due mainly to their strong size dependent properties and excellent chemical processibility. CdSe nanocrystals were synthesized by using sol-gel process. Synthesized CdSe quantum dots were studied to evaluate the optical, electronic and structural properties using UV-absorption, and photoluminescence (PL) measurement. Prepared CdSe nanoparticles were subjected to sense hydrofluoric acid. Photoluminescence was quenched upon adding of hydrofluoric acid.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1993년도 제45차 추계 학술대회 연제집
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• pp.107-108
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• 1993

• 공업화학
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• 제2권1호
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• pp.77-85
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• 1991

염산 및 불산으로 모더나이트를 처리하여 실리카/알루미나 비가 다른 일련의 시료를 만들었다. 이러한 시료에 대하여 암모니아 TPD와 피리딘 흡착으로 IR을 이용하여 산성도를 측정하고 o-xylene 반응의 활성과 이성화반응에 대한 선택성을 측정하였다. 그 결과 염산처리 시료는 실리카/알루미나 비가 증가할수록 구조알루미늄이 추출되어 산량이 감소하였으며 실리카/알루미나 비가 22인 시료가 다른 시료들보다 활성이 좋았다. 불산처리 시료는 불산처리 시 불소가 구조 중 규소원자와 결합하였으며 처리시간이 증가함에 따라 결합된 불소는 증가하였다. 이 경우의 활성은 염산처리와는 달리 알루미늄의 추출과 함께 모더나이트의 수산기가 불소로 치환되어 이로 인하여 산점이 줄어 활성이 감소하나 불산은 규소도 추출하므로 표면을 파고들어 새로운 면이 노출되어 산점이 형성되고 이 산점은 증가된 결합불소의 영향을 받아 강해지면서 활성이 다소 증가하였다.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2006년도 춘계임시총회 및 제27회 학술발표대회
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• pp.47-55
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• 2006

실리콘웨이퍼 제조공정에서 발생되는 초산, 불산 및 질산을 함유한 3성분계 폐혼산으로부터 각 산을 분리하여 무기산으로 재활용하기 위하여 용매추출법을 적용하였다. 이러한 산을 선택적으로 분리하기 위해 추출제로 초산의 경우는 EHA(2-Ethylhexlalcohol)를 사용 하였으며 질산과 불산의 경우에는 TBP(Tri -butlyphosphate)를 사용하여 추출과정과 탈거과정에 대한 공정설계를 위한 기초 실험을 실시하였다. 3성분계 페혼산에서 먼저 초산을 추출 분리하고, 추출여액중 질산 및 불산을 순차적으로 연속 분리 할 수 있는 공정개발을 위하여 McCabe-Thiele해석을 통해 최적 투입유량비(O/A), 소요단수(Stage) 등을 결정하였다. 분석 결과 혼산으로부터 초산의 회수율은 90%이상 이었으며 초산추출여액에서 질산의 회수율은 90%이상, 최종 추출잔류액에서 불산의 회수율은 67%이상 이었다.

• 자원리싸이클링
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• 제16권1호
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• pp.59-67
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• 2007

실리콘 웨이퍼 제조공정 중 발생되는 초산, 질산 및 불산을 함유한 3성분계 폐혼산으로부터 개별산으로 분리하여 재활용할 목적으로 용매추출법을 적용하였다. 각 산의 분리를 위해 사용한 추출제로는 초산의 경우는 EHA(2-Ethylhexlalcohol)를 사용하였고, 질산과 불산의 경우에는 TBP(Tri-butylphosphate)를 사용하여 각 산의 분리과정에 대한 공정설계를 위한 기초 data를 얻고자 하였다. 3성분계 폐혼산에서 초산을 추출 분리하고 이후 추출여액 중 질산 및 불산을 순차적으로 추출 분리 할 수 있는 연속공정개발을 위하여 기초 실험 자료와 McCabe-Thiele해석을 통해 최적 투입유량비(O/A), 소요단수(Stage) 등을 결정하였다. 분석 결과 혼산으로부터 초산의 회수율은 90%이상 이었으며 초산 추출여액에서 질산의 회수율은 90%, 최종 추출잔류액에서 불산의 회수율은 67%이상 이었다.

• 대한임상독성학회지
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• 제11권2호
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• pp.106-113
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• 2013

Purpose: The purpose of this study is to verify the influence of a massive hydrofluoric acid spill on community health through patients who claimed to have been exposed. Methods: We analyzed 2459 patients who visited our emergency department with the claim of exposure to hydrofluoric acid, and retrospective analyses were performed. We analyzed changes in numbers of visitors per day from the day of the accidental hydrofluoric acid spill, symptoms presented by the 1924 patients, and general characteristics. Comparisons of symptoms and hematologic characteristics were made between the initially set evacuation zone(1.3 km radius parameters from the spill) and the outer zone. Results: A total of 2,459 patients who claimed exposure visited our ED from 27 September 2012 to 23 October 2012, and there was a significant increase in the number of visiting patients from day 8 of the hydrofluoric acid spill. The most common complaints were a sore throat, 729(37.9%) and no specific symptom with health concern, 547 (28.4%). Statistically significant findings were pulmonary symptoms (p=0.001), nasal symptoms (p=0.001), diarrhea (p=0.023), and skin symptoms (p=0.007). In hematologic study, a statistically significant difference was observed in white blood cell count (p=0.018), creatine phosphokinase (p<0.001), erythrocyte sediment rate (p=0.013), and phosphorus (p<0.001). Conclusion: A significant increase in the number of patients was observed one week after the accidental spill of hydrofluoric acid. The most frequent symptoms were sore throat, headache, cough, and sputum. Statistically significant increase in creatine phosphokinase level and decrease in phosphorus level were noted in patients within the evacuation zone.

• 대한임상독성학회지
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• 제7권2호
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• pp.121-126
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• 2009

Purpose: We investigated the clinical characteristics and demographics of patients who suffered from hydrofluoric acid chemical injury and the mechanism of damage. Methods: We retrospectively reviewed the medical records of patients who were exposed to hydrofluoric acid from March 2004 to March 2009 and who were seen at the emergency centers in two university teaching hospitals. Results: Forty four patients out of 47 patients suffered from chemical burn, while the injuries of the remaining 3 could not be identified by the medical records. A total of 17 hydrofluoric acid chemical injury patients were enrolled during the study period, and their mean age was $29.6{\pm}7.0$. All the patients were accidentally injured by contact with the material and none of them inhaled or ingested the material. Only 6 patients wore appropriate protective equipments and 5 underwent the water irrigation for more than 10 minutes. The most common exposure area was the hand and forearm (70.5%). Less than 1% of all of the patients had their total body surface (TBS) exposed to hydrofluoric acid (mean=0.35%). The mean time interval from calcium gluconate administration to pain relief was $33.6{\pm}8.8$ hours. Conclusion: When exposed to hydrofluoric acid, it is important to wear protective equipment and undergo water irrigation for more than 10 minutes. Pain and skin damage were observed in all the patients. After treatment, we concluded that administration of calcium gluconate and pain killers was successful in relieving pain, and the prognosis was also positive for the admitted and followed up patients when less than 1% of the TBS was exposed.

• The Journal of Advanced Prosthodontics
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• 제8권4호
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• pp.267-274
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• 2016

PURPOSE. This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). MATERIALS AND METHODS. Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (${\alpha}$=.05). RESULTS. Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05). CONCLUSION. Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia.

• 한국환경보건학회지
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• 제40권1호
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• pp.27-37
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• 2014

Objectives: On September 27, 2012, leakage of anhydrous hydrofluoric acid occurred in a chemical plant in the Gumi National Industrial Complex. Following the accident, local factory workers and residents complained of abnormal health conditions. In addition, visual discolorations were widely observed in crops and trees in surrounding areas. The main objectives of the present study were to identify the area that was affected by the spill using data obtained from plants, soil, and water samples after the accident. Methods: Fluoride concentrations were analyzed in pine tree needles, soil, nearby streams, ponds and reservoirs collected from an area within a radius of three kilometers from the plant where the leak occurred. Fluoride concentrations in the air at the time of leakage were then estimated from fluoride concentrations that were measured in the pine tree needles. A Kriged map was developed to describe the spatial distribution of hydrofluoric acid at the time of the leakage and was compared with the area designated as a Special Disaster Zone by the government. Results: The Special Disaster Zone did not include all the affected area that was estimated by the Kriged map. Analytical results of the environmental samples also supported this discrepancy. Conclusion: Using plants, atmospheric concentrations of fluoride at the time of the leakage could be estimated. For the area that was identified as affected, further public health risk assessment and environmental risk assessment should be considered. Also, in the absence of air monitoring at the time of leakage, studies employing plants may be conducted in order to better understand the spatial extent and severity of the contamination.

• 열처리공학회지
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• 제31권1호
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• pp.6-11
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• 2018

The anodic oxidation behavior of Si-containing aluminum alloy for diecasting was investigated. Especially, the property changes during anodization both on aluminum 1050 and 9 weight percentage silicon containing aluminum (Al-9Si) alloys were analyzed by the static current test. In order to fabricate a uniform anodic oxidation film by effect of Al-Si compound, nitric acid containing hydrofluoric acid had been used as a desmutter for aluminum alloy after alkaline etching. It was found that the level of voltage of Al-9Si alloy during the static current test was almost as double as higher than aluminum 1050 through anodization. By adding hydrofluoric acid in the nitric acid electrolyte, the silicon compound on the surface was removed, and the optimum amount of added hydrofluoric acid could be derived. It was also observed that the size of silicon compound formed on the surface could be refined by heat treatment at $500^{\circ}C$ and followed water quenching.