• 광물과산업
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• 제25권
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• pp.1-10
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• 2012

본 연구에서는 경북 울진 보암광산의 리튬광을 대상으로 고품위 리튬 정광 생산을 위한 부유선별 연구를 수행하였다. 리튬의 근원광물은 Lepidolite (0.99% $Li_2O$)이며, 주요 맥석광물은 $SiO_X$를 포함하는 규산염 광물(quartz, muscovite)과 방해석(Calcite)이 존재하였다. 따라서 음이온포수제를 이용하여 방해석을 먼저 부유시켜 제거하고, 규산염 광물을 억제하고 리튬 광물을 부유시키는 공정을 적용하였다. 리튬광물 부유선별에서 포수제는 아민계통의 양이온 포수제(Armac-T, Armac-C, Armafloat-18, Armafloat-1597) 중 Armac-T가 가장 효과적이었다. 실험결과 최적 조건인 포수제(Armac-T) 100g/t, 기포제(AF65) 50g/t, 억제제($Na_2SiO_3$) 600g/t, (Lactic acid) 100g/t, 광액농도 20%solids, pH 5.5 그리고 정선횟수 2회에서 $Li_2O$의 품위와 회수율이 각각 4.33%와 80.3%인 결과를 얻었다.

• 마이크로전자및패키징학회지
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• 제16권3호
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• pp.53-59
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• 2009

PCB 표면 개질 및 세정에 있어서 저압 수은 램프를 이용한 UV 장비가 널리 사용되어왔다. 본 연구에서는 공정의 생산성을 향상 시키기 위하여 기존 UV 장비를 대체하여 리모트 DBD 방식의 대기압플라즈마 장비를 새로이 개발하였다. 두 장비의 생산성 비교는 처리 시간 증가에 따른 표면 접촉각의 변화를 측정함으로써 정량적으로 비교할 수 있었다. 측정 결과 대기압 플라즈마 장비의 생산성이 UV 장비에 비하여 매우 우수한 것으로 확인 되었다. 또한 XPS를 이용한 표면 조성 측정 결과 동일한 접촉각 수준에서 UV 및 대기압 처리의 효과는 유사한 것으로 파악되었다. 즉, 유기 오염 수준이 감소되었으며 표면 일부 표면 원소가 산회되었다. 최종적으로 대기압 플라즈마를 BGA제조의 플럭스 도포 공정에 적용하였는데, 대기압 플라즈마를 처리함으로써 도포 공정의 균일도가 향상되는 결과를 얻을 수 있었다.

• 식품보건융합연구
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• 제6권5호
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• pp.19-25
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• 2020

The purpose of this study was to research and develop a step-type chemical liquid deodorizer including a liquid catalyst that can prevent civil complaints due to odor due to its excellent deodorizing performance. The main composition of chemical liquid deodorizer including liquid catalyst is cleaning deodorization, catalyst deodorization, chemical deodorization, water film plate, deodorization water circulation device, deodorization water injection device, catalyst management system, gas-liquid separation device, chemical supply device, deodorizer control panel, etc. It consists of a device. The air flow of the step-type liquid catalyst chemical liquid deodorizer is a technology that firstly removes basic odor substances, and the liquid catalyst installed in the subsequent process stably removes sulfur compounds, which are acidic odor substances, to discharge clean air. The efficiency of treating the complex odor of the prototype was 98.5% for the first and 99.6% for the second, achieving the target of 95%. The hydrogen sulfide treatment efficiency of the prototype was 100% for the first and 99.9% for the second, which achieved 95%, which was the target of the project. As a result, ammonia was removed by the reaction of ammonia and hydrogen sulfide.

• 한국미생물·생명공학회지
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• 제48권2호
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• pp.99-112
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• 2020

유류 오염 토양을 환경친화적으로 정화하는 방법으로 식물과 근권미생물 사이의 생태적 상승작용(synergism)에 기반을 둔 rhizoremediation이 큰 주목을 받고 있다. 전지구적 문제인 기후변화에 대응하기 위해서는 오염 토양을 정화하는 과정에서 온실가스 배출량을 최소화할 수 있는 기후변화 대응 정화기술이 도입될 필요가 있다. 기후변화 대응 rhizoremediation 기술에서, 오염정화효율과 non-CO₂ 온실 가스 배출량에 영향을 미치는 주요인자는 오염물질 특성 및 토양의 물리화학적 특성 뿐 아니라, 식물-미생물 상호작용, 미생물 활성, 그리고 첨가제 및 강화제 첨가 여부로 구분할 수 있다. 본 총설에서는 유류 오염토양을 정화하기 위한 rhizoremediation 기술 개발 동향을 정리하고, 기후변화 대응 rhizoremediation 기술 개발 방향에 대해 고찰하였다.

• 방사성폐기물학회지
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• 제16권2호
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• pp.173-182
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• 2018

원자력 시설 내 방사능을 포함하는 물질의 제염을 위한 방법 중 거품제염은 2차폐기기물의 양을 저감시킬 수 있는 장점을 지니고 있다. 본 연구에서는 거품안정성을 증가시킬 수 있는 실리카 나노입자를 여러가지 조건을 달리하여 합성하였다. Cetyltrimethylammonium bromide(CTAB)는 거품제염제의 거품안정성에 많은 영향을 나타내었다. 이러한 거품안정성이 향상된 이유는 제염제 내에 공기와 용액간의 계면에서 실리카 나노입자와 계면활성제의 반응으로 생각된다. 또한, CTAB는 실리카나노입자의 분리특성에서도 우수한 성능을 나타냈었다. 실리카 나노입자 분리시, CTAB의 탄화수소기에 의한 소수성과 전하중성화에 의해서 실리카 나노입자의 응집현상을 향상시켰다.

• Restorative Dentistry and Endodontics
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• 제41권2호
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• pp.106-113
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• 2016

Objectives: This study evaluated the effects of different surface conditioning methods on the bond strength of orthodontic brackets to glazed full-zirconia surfaces. Materials and Methods: Glazed zirconia (except for the control, Zirkonzahn Prettau) disc surfaces were pre-treated: PO (control), polishing; BR, bur roughening; PP, cleaning with a prophy cup and pumice; HF, hydrofluoric acid etching; AA, air abrasion with aluminum oxide; CJ, CoJet-Sand. The surfaces were examined using profilometry, scanning electron microscopy, and electron dispersive spectroscopy. A zirconia primer (Z-Prime Plus, Z) or a silane primer (Monobond-S, S) was then applied to the surfaces, yielding 7 groups (PO-Z, BR-Z, PP-S, HF-S, AA-S, AA-Z, and CJ-S). Metal bracket-bonded specimens were stored in water for 24 hr at $37^{\circ}C$, and thermocycled for 1,000 cycles. Their bond strengths were measured using the wire loop method (n = 10). Results: Except for BR, the surface pre-treatments failed to expose the zirconia substructure. A significant difference in bond strengths was found between AA-Z ($4.60{\pm}1.08MPa$) and all other groups ($13.38{\pm}2.57-15.78{\pm}2.39MPa$, p < 0.05). For AA-Z, most of the adhesive remained on the bracket. Conclusions: For bracket bonding to glazed zirconia, a simple application of silane to the cleaned surface is recommended. A zirconia primer should be used only when the zirconia substructure is definitely exposed.

• 대한방사선기술학회지:방사선기술과학
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• 제24권2호
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• pp.65-70
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• 2001

The purpose of this study is to prevent nosocomial infection in patients through contact of radiographic cassettes. Data were collected from radiographers working in 29 university hospitals in Seoul in February and March 2001. Radiographic cassettes were disinfected daily in 5 hospitals, weekly in 4 hospitals, monthly in 5 hospitals, bimonthly in 1 hospital and once every three months in another hospital. 12 other hospitals do not practice regular disinfections of radiographic cassettes. Gauze soaked in disinfectant solution is used in 7 hospitals while 11 hospitals used cotton and cloth soaked in disinfectant solution to clean the radiographic cassettes. 26 hospitals used 99% alcohol based disinfectant solutions while 3 hospitals used 75% alcohol based disinfectant. 26 hospitals use of intercourse cassettes outpatients and in patients. In 26 hospitals, all patients shared the same set of radiographic cassettes used in the hospitals, or in 26 hospitals, separate sets of radiographic cassettes are used for outpatients and inpatients. Separate sets of cassettes are used for ICU and inpatients in 6 others hospitals. 23 hospitals used the same sets of radiographic cassettes for all their patients. radiographic cassettes are cleaned in wash area in the study room of the radiographic department in 17 hospitals. 12 other hospitals do not have designated cleaning areas for the cassettes. All radiographers practiced hands washing with soap. All 29 hospitals surveyed have infection control committee. However, only 9 out of the 29 hospitals surveyed provided Infection disinfections control education to radiographers. Only 3 hospitals have radiographers sitting in the infection control committee. Infection management education is conducted in 63 hospitals annually, twice a year in 1 hospital and once every 3 months in 2 hospitals.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.465-469
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and tested for hydrogen production via anaerobic fermentation of sucrose. Each reactor consisted of a column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed with changing flow rate into the capped reactor, hydraulic retention time and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% for all conditions tested. Hydrogen production rates increased up to $10.5 L{\cdot};h^{-1}{\cdot}L^{-1}$ of reactor when influent sucrose concentrations and recycle rates were varied. Hydrophobic media provided higher value of hydrogen production rate than hydrophilic media at the same operation conditions. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate and butyrate. The reactor filled with hydrophilic media became clogged with biomass and bio gas, requiring manual cleaning of the system, while no clogging occurred in the reactor with hydrophobic media. In order to make long-term operation of the reactor filled with hydrophilic media feasible, biofilm accumulation inside the media in the reactor with hydrophilic media and biogas produced from the reactor will need to be controlled through some process such as periodical backwashing or gas-purging. These tests using trickling bed biofilter with hydrophobic media demonstrate the feasibility of the process to produce hydrogen gas in a trickle-bed type of reactor. A likely application of this reactor technology could be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.617-626
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• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.

• 한국농공학회논문집
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• 제61권6호
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• pp.21-30
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• 2019

Livestock odor is comprised of mixed type of odorous compounds. Among these, ammonia ($NH_3$) and hydrogen sulfide ($H_2S$) are the two known major odor causing substances. Because high odor concentration reduces productivity of livestock and causes damage to the surrounding communities, quantitative analysis is needed to manage the odor inside and outside the livestock facilities. It is also necessary to evaluate odor dispersion according to the distance between the receptors taking into account the influence of odor source and weather condition. Therefore, in this study, we tried to evaluate the internal environment and odor dispersion from experimental pig house considering weather conditions. An experimental farm was specifically selected to eliminate the interference of odors generated by adjacent farms. $NH_3$ and complex odor were quantitatively analyzed using a gas detector and air dilution sensory method. The concentration of $NH_3$ and complex odor in pig house showed a distinct concentration difference according to the cleaning and ventilation conditions. $NH_3$ concentration and complex odor was lower than emission standard in the pig house and at the site boundary. The average $NH_3$ concentration (P1~P3) and the $NH_3$ concentration at the site boundary (S1) were strongly correlated with R=0.77. While the correlation for complex odor inside and at the site boundary had R=0.52. The correlation coefficient between $NH_3$ and the complex odor was 0.80.