• 한국해양학회지
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• v.22 no.3
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• pp.191-206
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• 1987

Keum River discharges 6.4billion tons of fresh water annually into the Yellow Sea. More than 60% of the total discharge is concentrated in summer, differentiating distinct low-discharge and high-discharge periods for the estuarine environment. The concentration of SPM(Suspended Particulate Matter) is, in general, very high, except sometime during rainy season, and turbidity maximum is often observed, especially during spring-tides(Lee and Kim, 1987).

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.480-480
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• 2011

양극산화(anodization)는 금속을 전기화학적으로 산화시켜 금속산화물로 만드는 기술로서 최근 다양한 크기의 나노 구조를 제조하는 기술로 각광받고 있으며, 이러한 기술에 의하여 얻어지는 anodic aluminum oxide(AAO)는 magnetic data storage, optoelectronic device, sensor에 적용될 수 있는 nano device 뿐만 아니라 nanostructure를 제조하기 위한 template 및 mask로써 최근 광범위 하게 연구되고 있다. 또한, AAO는 Al2O3의 단단한 구조를 가진 무기재료이므로 solid mask로써 다른 porous materials 보다 뛰어난 특성을 갖고 있다. 또한 electron-beam lithography 및 block co-polymer 에 의한 patterning 과 비교하여 매우 경제적이며, 재현성이 우수할 뿐만 아니라 대면적에서 나노 구조의 크기 및 형상제어가 비교적 쉽기 때문에 널리 사용되고 있다. 그러나, AAO 형성 시 생기게 되는 반구형 모양의 barrier layer는 물질(substance)과 기판과의 direct physical and electrical contact을 방해하기 때문에 해결해야 할 가장 큰 문제점 중 하나로 알려져 있다. 따라서 본 연구에서는 실리콘 기판위의 형성된 AAO의 barrier layer를 Cl/BCl3 gas mixture에서 Neutral Beam Etching (NBE)과 Ion Beam Etching (IBE) 로 각각 식각한 후 그 결과와 비교하였다. NBE와 IBE 모두 Cl2/BCl3 gas mixture에서 BCl3 gas의 첨가량이 60% 일 경우 etch rate이 가장 높게 나타났고, optical emission spectroscopy (OES)로 Cl2/BCl3 플라즈마 내의 Cl radical density와 X-ray photoelectron spectroscopy (XPS)로 AAO 표면 위를 관찰한 결과 휘발성 BOxCly의 형성이 AAO 식각에 크게 관여함을 확인 할 수 있었다. 또한, NBE와 IBE 실험한 다양한 Cl2/BCl3 gas mixture ratio 에서 AAO가 식각이 되지만, 이온빔의 경우 나노사이즈의 AAO pore의 charging에 의해 pore 아래쪽의 위치한 barrier layer를 어떤 식각조건에서도 제거하지 못하였다. 하지만, NBE에서는 BCl3-rich Cl2/BCl3 gas mixture인 식각조건에서 AAO pore에 휘발성 BOxCly를 형성하면서 barrier layer를 제거할 수 있었다.

• Membrane Journal
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• v.30 no.3
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• pp.149-157
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• 2020

Ionic Liquid (IL) in the category of low-temperature molten salts with organic cation and organic/inorganic anion has shown great potentiality in CO₂ gas separation. CO₂ gas separation from flue gas by IL based membrane has been widely researched in recent years to overcome climate change and global warming. Membranes based on free standing polyionic liquid (PIL), blend of ionic liquid and composite ionic liquid membranes are discussed in this review. Introducing different IL monomers and tuning microstructure of PIL membrane and composite of PIL-IL to enhance mechanical properties of membranes with good CO₂ gas permeability and selectivity. Variations in cation and anions of monomer has great impact on the membrane gas separation performance.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.179-184
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• 2008

The separation and purification of succinate are necessary for the succinic acid production by a fermentation process. Among the purification processes, desalination of succinate is inevitable. In this work, electrodialysis was selected as a desalination method and its operating parameters affecting the degree of desalination and energy consumption were examined. Commercialized electrodialysis apparatus was used in this work and its optimum operating parameters were determined by using design of experiment (DOE) method. Voltage, concentration of succinate, and pH were selected as main parameters. Among them, voltage seemed to be the most important one. The final conversion of succinate to succinic acid was calculated when the operating parameters were optimized. Finally, the effect of impurities, such as corn steep oil, yeast extract, and dextrose on the electrodialysis efficiency was also studied.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.160-164
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• 1999

Algicidal activities of Alteromonas sp. SR-14 against Chaetoceros calcitrans were investigated at various culture conditions. The algicidal activity by Alteromonas sp. SK-14 was dependent on temperature. In mixed culture of C, calcitrans and Alteromonas sp. SR-14 at various temperatures, the algicidal activity of Alteronzonas sp. SR-14 was the highest at $20^{\circ}C$, but not showed algicidal activity above $25^{\circ}C$. With the inoculation of $10^4$ cells/ml of C. calcitrans, the diatom could not grow at the microalgal culture condition until 15 days by the simultaneous inoculation of less than 10 cells/ml of Alteromonas sp. SR-14. Alteromonas sp. SR-14 showed the strongest algicidal activity against logarithmic phase cells of C. calcitrans. During the mixed culture of C. calcitrans and Alteromonas sp. SR-14, supplementation of Conwy medium nutrients, changes of light intensity with 1,300$\~$4,600 lux and agitation with 200 rpm did not affect the algicidal activity.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.179-190
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• 2008

Purpose: In this study, the effect of micro-macroporous biphasic calcium phosphate(MBCP) incorporated with inorganic polyphosphate for bone regeneration in the calvaria of rabbit was evaluated. Materials and Methods: The procedure of guided bone regeneration was performed with titanium reinforced expanded polytetrafluoroethylene(TR-ePTFE) membrane. Four animal groups were compared : 1) TR-ePTFE membrane for negative control group, 2) TR-ePTFE membrane filled with MBCP for positive control group, 3) TR-ePTFE membrane filled with MBCP soaked in 4% inorganic polyphosphate for experimental group I, and 4) TR-ePTFE membrane filled with MBCP soaked in 8% inorganic polyphosphate for experimental group II. Results: 1. Negative control group showed the highest new bone formation at 16 weeks. 2. Positive control group showed the smallest new bone formation compared to other groups. 3. 8% inorganic polyphosphate induced more volume of bone formation, otherwise experimental group II did not show significant difference compared to negative control group. Conclusion: These results suggest that inorganic polyphosphate has a promoting effect on bone regeneration, possibly by enhancing osteoconductivity of the carrier and by increasing osteoinductivity of the defected alveolar bone tissue.

• KSBB Journal
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• v.11 no.6
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• pp.636-641
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• 1996

The production of extracellular mannitol by a new mannitol-producing bacterium, Leuconostoc sp. KY-002 was studied in shake flask cultures. The new isolate has a capability of utilizing fructose and sucrose for mannitol formation. Maximum mannitol production was obtained with fructose as the sole carbon source. Under the optimal culture conditions, within 70 hours of incubation, a final concentration of 26 g/L of mannitol from 50 g/L fructose was obtained with an indicated yield of 52% based on fructose consumed. However, higher concentrations of fructose ranging from 100 to 250 g/L could not effectively be transformed to mannitol due to a lack of osmotolerance. The strain produced no other polyols such as glycerol and sorbitol as by-products. Yeast extract was the best nitrogen source and high levels of inorganic phosphate up to 10 g/L promoted mannitol formation. Any mineral ions and salts did not play important role in both cell growth and mannitol production. Nicotinic acid enhanced mannitol production by 16%. The optimum culture temperature and initial pH were $35^{\circ}C$ and 6, respectively.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.491-510
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• 2005

This study was performed to evaluate the effect of inorganic polyphosphate on bone formation in the calvaria of rabbit in the procedure of guided bone regeneration with bovine cancellous bone graft and titanium reinforced expanded polytetrafluoroethylene(TR-ePTFE) membrane. The rabbits were divided into four groups. Control group I used only TR-ePTFE membrane, control group II used TR-ePTFE membrane and deproteinized bovine bone mineral soaked in saline, experimental group III and IV used TR-ePTFE membrane and deproteinized bovine bone mineral soaked in 1% or 2% inorganic polyphosphate respectively. After decortication in the calvaria, GBR procedure was performed on 12 rabbits with titanium reinforced ePTFE membrane filled with deproteinized bovine bone mineral soaked in saline or inorganic polyphosphate. The animals were sacrificed at 2 weeks, 4 weeks, and 8 weeks after the surgery. Decalcified and non-decalcified specimens were processed for histologic and immunohistochemistric analysis. 1. Titanium reinforced ePTFE(TR-ePTFE) membrane showed good spacemaking and cell occlusiveness capability, but it showed poor wound stabilization. 2. The deproteinized bovine bone mineral did not promote bone regeneration, but it acted as a space filler. 3. There was no complete resorption of the deproteinized bovine bone mineral within 8 weeks. 4. 1% inorganic polyphosphate did not promote bone formation, but 2% inorganic polyphosphate promoted bone formation. Within the above results, 2% inorganic polyphosphate could be used effectively for bone regeneration.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.447-447
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• 2010

일찍이 $SiO_2$ (Silicon dioxide) 박막은 다양한 분야에서 유전층, 부식 방지층, passivation층 등의 역할을 해왔다. 그리고 이러한 박막 공정은 대부분 진공의 환경에서 그 공정이 이루어지고 있다. 하지만 이러한 진공 system은 chamber, loadlock 그리고 펌프 등의 다양한 진공장비로 인한 생산 비용 증가, 공정의 복잡성뿐만 아니라 공정의 대면적화에 어려움을 지니고 있다. 그리고 최근 flexible display의 제조 공정에서 polymer 혹은 plastic 기판을 제조 공정에 적용시키기 위해 저온 공정이 필수적으로 요구 되고 있다. 이러한 기술적 한계를 뛰어 넘기 위해 최근 많은 연구가들은 atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD)에 대해 지속적으로 다양한 연구를 하고 있다. 본 연구에서는 remote-type의 modified pin-to-plate dielectric barrier discharge (DBD) 시스템을 이용한 $SiO_2$ 무기 박막 증착에 관해 연구하였다. $O_2$/He/Ar의 gas와 5 kV AC power (30 kHz)의 전원장치를 통해 고밀도 대기압 플라즈마를 발생시켰고, silicon precursor로는 hexamethyldisilazane (HMSD)를 사용하였다. 먼저 HMDS와 $O_2$ gas의 flow rate 변화에 따른 증착률을 조사하였고 그 다음으로 박막의 조성 및 표면 특성을 조사하였다. HMDS의 유량이 100 ~ 300 sccm으로 증가함에 따라 증착속도는 증가했다. 하지만 FT-IR을 통해 HMDS의 유량이 증가하면 반응에 참여할 산소 분자의 부족으로 인해 $-(CH_3)_X$의 peak intensity가 증가하고, -OH의 peak intensity가 점차 감소함을 관찰 할 수 있었다. 또한 증착된 박막의 표면에 particle과 불균일한 surface morphology 등을 SEM image를 통해 관찰 하였다. 산소 유량이 탄소와 관련된 많은 불순물들의 제거에 도움이 됨에도 불구하고 14 slm 이상의 산소가 반응기 내로 주입되게 되면 대기압 플라즈마의 discharge가 불안정하게 되어 공정효율을 저하시키는 요소가 되었다. 결과적으로 HMDS (150 sccm)/$O_2$ (14 slm)/He (5 slm)/Ar (3 slm)의 조건에서 약 42.7 nm/min 증착률을 가지며, 불순물이 적고 surface morphology가 깨끗한 $SiO_2$ 박막을 증착할 수 있었다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.389-399
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• 2019

The calcium carbonate saturation state in the Ulleung Basin of East Sea was calculated using bottle data set of pH, dissolved inorganic carbon and total alkalinity obtained from the year 1999, 2014, 2017, and 2018 cruise. In the 2010s calcium carbonate saturation state was significantly lowered at all depth compared to the 1999 reference state. Accordingly calcite saturation horizon and aragonite saturation horizon shoaled to 500 m and 200 m, respectively. A key chemical species for the calcium carbonate saturation state, carbonate ion showed distinctive profile between upper and deep waters: it is moderately high (${\sim}175{\mu}mol\;kg^{-1}$) in upper waters and very low (< ${\sim}50{\mu}mol\;kg^{-1}$) in the deep waters. However the decreasing trend of carbonate ion concentration was pronounced in the upper water than deep waters, suggesting atmospheric $CO_2$ penetration is largely confined to the upper waters in the 2000s.