• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1670-1679
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• 2015

Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH₄⁺-N/m³/d and 0.10-0.21 kg NO₃^--N/m³/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH₄⁺ or NO₃^- loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs.

• 한국재료학회지
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• 제27권11호
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• pp.590-596
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• 2017

We demonstrated a CNT synaptic transistor by integrating 6,6-phenyl-C61 butyric acid methyl ester(PCBM) molecules as charge storage molecules in a polyimide(PI) dielectric layer with carbon nanotubes(CNTs) for the transistor channel. Specifically, we fabricated and compared three different kinds of CNT-based synaptic transistors: a control device with $Al_2O_3/PI$, a single PCBM device with $Al_2O_3/PI:PCBM$(0.1 wt%), and a double PCBM device with $Al_2O_3/PI:PCBM$(0.1 wt%)/PI:PCBM(0.05 wt%). Statistically, essential device parameters such as Off and On currents, On/Off ratio, device yield, and long-term retention stability for the three kinds of transistor devices were extracted and compared. Notably, the double PCBM device exhibited the most excellent memory transistor behavior. Pulse response properties with postsynaptic dynamic current were also evaluated. Among all of the testing devices, double PCBM device consumed such low power for stand-by and its peak current ratio was so large that the postsynaptic current was also reliably and repeatedly generated. Postsynaptic hole currents through the CNT channel can be generated by electrons trapped in the PCBM molecules and last for a relatively short time(~ hundreds of msec). Under one certain testing configuration, the electrons trapped in the PCBM can also be preserved in a nonvolatile manner for a long-term period. Its integrated platform with extremely low stand-by power should pave a promising road toward next-generation neuromorphic systems, which would emulate the brain power of 20 W.

• 한국물환경학회지
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• 제25권1호
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• pp.58-68
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• 2009

Low impact development (LID) technique is relatively new concept to reduce surface runoff and pollutant loading from land cover by attempting to match predevelopment condition with various integrated management practices (IMPs). In this study, computational model for designing and evaluating LID, named LIDMOD, was developed based on SCS-CN method and applied at Andong bus terminal to evaluate LID applicapability and design retention/detention area for volume or peak flow control. LIDMOD simulated with 21 years simulation period that yearly surface runoff by post-development without LID was significantly higher than that with LID showing about 2.8 times and LID could reduce efficiently yearly surface runoff with 75% reduction of increased runoff by conventional post development. LIDMOD designed detention area for volume/peak flow control with 20.2% of total area by hybrid design. LID can also efficiently reduce pollutant load from land cover. Pollutant loads from post-development without LID was much higher than those from pre-development with showing 37 times for BOD, 2 times for TN, and 9 times for TP. Pollutant loads from post-development with LID represented about 57% of those without LID. Increasing groundwater recharge reducing cooling and heating fee, creating green refuge at building area can be considered as additional benefits of LID. At the point of reducing runoff and pollutant load, LID might be important technique for Korean TMDL and LIDMOD can be useful tool to calculate unit load for the case of LID application.

• 한국토양비료학회지
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• 제42권4호
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• pp.239-248
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• 2009

본 실험은 지하수에 포함된 중금속을 제거하기 위한 투수성반응벽체를 개발하기 위하여 대공극 형성물질로 분쇄한 폐지와 식물섬유를 그리고 구조형성소재로 Na와 Ca-벤토나이트를 사용하여 소성 후 소성된 소재의 표면 구조와 공극발달 특성을 조사하였다. 그러나 소성은 중금속 제거율을 급격히 감소시키는 양이온교환용량에 영향을 미치므로 2:1 점토광물 중에서 양이온교환용량이 큰 점토광물과 일반 산업물질을 소재를 선정하였다. 연구 결과는 살펴보면 소성온도가 증가함에 따라 소성에 사용된 소재의 기존 CEC의 10 % 이하로 급격히 감소되는 경향을 보여주었다. 일축 압축 시험 결과 처리간 용적밀도는 큰 차이가 없었지만 Na와 Ca-벤토나이트를 소성소재 모두 폐지가 5 % 정도 처리하였을 때 압축강도가 가장 높은 것으로 나타났다. 그리고 소성온도와 기간 모두 공극 형성에 영향을 미친 것으로 조사되었다. 이러한 연구 결과로부터 다공체 내에 형성된 공극은 수분 투수 특성과 중금속 제거에 모두 영향을 미칠 것이라 추정하였다.

• 한국식품저장유통학회지
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• 제13권3호
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• pp.279-284
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• 2006

저장방법에 따른 삼백초 생근경의 품질과 유효성분 함량의 변화를 조사하였다. 감모율과 부패율 및 맹아수는 저장기간이 경과할수록 증가하거나 많았다. 감모정도와 맹아수는 저온저장에서 가장 적었으며, 부패율은 창고 내 흙 충진 저장에서 낮았다. 삼백초 근경의 chromatogram상 각 성분의 머무름시간(RT)은 $18{\sim}36$분대로 saucernetin>sauchinone>manassantin A>saucerneol D>manassantin B의 순으로 나타났다. Lignans의 함량은 저장방법 모두 저장 후 30일에 비해 120일에 낮았으나, 저장방법간에는 차이가 없었고 manassantin B>manassantin A>saucernetin>sauchinone>saucerneol D의 순으로 함량이 높았다.

• 대한치과교정학회지
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• 제41권2호
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• pp.138-146
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• 2011

The purpose of this article is to introduce a new virtual orthodontic treatment (VOT) system, which can be used to construct three-dimensional (3D) virtual models, establish a 3D virtual setup, enable the placement of the virtual brackets at the predetermined position, and fabricate the transfer jig with a customized bracket base for indirect bonding (IDB) using the stereolithographic technique. A 26-year-old woman presented with anterior openbite, crowding in the upper and lower arches, and narrow and tapered upper arch, despite having an acceptable profile and balanced facial proportion. The treatment plan was rapid palatal expansion (RPE) without extraction. After 10 days of RPE, sufficient space was obtained for decrowding. After a 10-week retention period, accurate pretreatment plaster models were obtained using silicone rubber impression. IDB was performed according to the protocol of the VOT system. Crowding of the upper and lower arches was effectively resolved, and anterior openbite was corrected to normal overbite. Superimposition of the 3D virtual setup models (3D-VSM) and post-treatment 3D virtual models showed that the latter deviated only slightly from the former. Thus, the use of the VOT system helped obtain an acceptable outcome in this case of mild crowding treated without extraction. More cases should be treated using this system, and the pre- and post-treatment virtual models should be compared to obtain feedback regarding the procedure; this will support doctors and dental laboratory technicians during the learning curve.

• 통상정보연구
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• 제8권3호
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• pp.299-321
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• 2006

The purpose of this study was to analyze export competitiveness of Korean auto parts and Chinese auto parts in U.S. market by using Index of Export Bias and Market Comparative Advantage Index. For attaining the purpose of study, we classified the auto parts which exported to U.S. market and the imported products by using the six units classification of the Harmonized System(HS). Analyzing period was 1998-2005. The analysis of Korean results of MCA indicated that the Korean auto parts which gained export competitiveness in the U.S. market were HS Code No. 8708.94, 8708.99, 8708.92. The products which will have export competitiveness in the U.S. market would be HS Code No. 8708.93, 8708.39, 8708.60 respectively. On the other hand, the results indicated that the Chinese auto parts which gained export competitiveness in the U.S. market were HS Code No. 8708.70, 8708.31, 8708.91, 8708.60, 8708.39. From this study, we find the following strategies for successful advancing into the U.S. and world market. i) Linking strategy through working cooperation with local auto firms, government and academic world. ii) Advance strategy of auto firm accompany by module working and system auto parts firm. iii) Retention strategy of large technical institution established by auto parts firms and taking cooperation of auto firms iv) Settlement strategy for having weaken competitive article and production field. v) Cost-cutting strategy through strengthening logistics cooperation system between auto parts firms and auto firms. vi) Active invitation strategy of foreign investment under quickly cooperating of government.

• 한국환경보건학회지
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• 제29권4호
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• pp.27-34
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• 2003

Bisphenol A is used in the manufacture of epoxy, polycarbonate, and corrosion-resistant unsaturated polyester-styrene resins required for food packaging materials in industrial processing. Some reports indicated the possibility of harmful effects on rats. In this study was used a method for the determination of bisphenol A in blood according to the OSHA High Performance Liquid Chromatography (HPLC) guideline. The method involved blood extraction using methylene chloride. And it was evaluated developmental and teratogenic effects in pregnant rats and second generation. The results obtained were as follows. There was a significant increase in the body weights and treated groups F1 female in liver, spleen, kidney, but according to dose-response. F1 female rat's relative body weight and absolute body weight are not different. There was a significant increase liver, spleen, kidney organ weight and reproductive organ weight epididymis, prostate gland in F1 male rats. There was a proestrous in pregnant rat, group 200 $\mu\textrm{g}$/kg, 2000 $\mu\textrm{g}$/kg, 20,000 $\mu\textrm{g}$/kg. The effect on rat treated with bisphenol A decrease organ weight and reproductive organ weight. Identification and quantitation were performed with using HPLC C18 column and using at retention time 5.5 min. The results of the detection of bisphenol A were at 20,000 $\mu\textrm{g}$/kg in average 1 $\mu\textrm{g}$/ml, 200 $\mu\textrm{g}$/kg average in 0.9 $\mu\textrm{g}$/ml blood samples. From those results, it could be concluded that the effects of pregnant rat and second generation(F1) by bisphenol A treatment during lactational period were estrogenic and bisphenol A was remained in serum at low level.

• 한국환경과학회지
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• 제21권12호
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• pp.1469-1476
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• 2012

Hydrophilic polymer is suitable as soil conditioners for green roofs that use rainwater, due to promotion of water retention capacity as well as enhancement of the water absorbing capacity. The objective of the present study was to investigate the effects of different levels of hydrophilic polymer concentrations (0, 0.1, 0.2, 0.4, 0.8% w/w) on the water holding capacity and growth response of 6 species in soils amended with hydrophilic polymer in 5 cm of soil thickness on green roofs. The results showed that the water holding capacity of the amended soil improved with increasing amount of applied polymer. The application of 0.8% w/w of the polymer increased the soil moisture by 87% compared to the control, and decreased slowly in green roofs during an arid period. The growth of Sedum spurium 'Dragon's blood' and Lampranthus spectabilis increased significantly and had greater than 60% relative coverage with higher hydrophilic polymer concentrations. However, Juniperus chinensis var. sargentii and Euonymus fortunei var. radicans had no significant differences upon change of hydrophilic polymer concentrations. In Carex kujuzana and Carex morrowii 'Aurea variegata', growth decreased with increase of hydrophilic polymer concentrations. 30 days after planting, Juniperus chinensis var. sargentii, Euonymus fortunei var. radicans, Carex kujuzana, and Carex morrowii 'Aurea variegata' died back due to lowest soil thickness (5 cm), but Sedum spurium 'Dragon's blood' and Lampranthus spectabilis had greater than 90% survival.

• 한국산업보건학회지
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• 제23권4호
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• pp.367-373
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• 2013

Objectives: Employee exposure record refers to a record containing information about environmental (workplace) monitoring or measuring of a toxic substance or harmful physical agent. The aims of this study were to examine problems related to exposure records and provide some amendments to the Korean Industrial Safety & Health Act for the effective management of chemical substances under the law. Methods: This study performed a literature search and review on legal provisions related to exposure records of a number of different countries, including Korea, the USA, Japan, EU, Germany, and the UK. They were compared and investigated and the amendment of articles was suggested. Results: The results of this study were provided as suggested amendments to the related act. There were a variety of ways of improvement, including a 30-year retention period and the introduction of new access methods, contents, transfer, and maintenance methods. All exposure data elements have to be standardized, including reference to a similar exposure group (SEG), sampling strategy, and circumstances of exposure (e.g., date, shift length, use of personal protective equipment, etc.). The SEGs are described by process, job, task, and environmental agent. Conclusions: This study is expected to provide for the amendment of the related act in order to ensure effective management of exposure records and is helpful for solving the cause and result of occupational disease by keeping exposure records according to the Industrial Safety & Health Act.