• Korean Journal of Microbiology
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• v.39 no.1
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• pp.21-26
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• 2003

Ninety strains of photosynthetic bacteria were isolated from a local stream at Kyonggi-do, Korea and were further screened. Using these isolated strains, experiments were performed under various light and oxygen conditions in order to select strains with high nitrogen $(NH_3-N,\; NO_3^--N)$ removal efficiencies. Results showed that all the strains screened removed $NH_3-N$, the light had no effect on nitrogen removal, and the nitrogen removal rate was higher aerobically than anaerobically. The removal of $NO_3^--N$ was showed up to 35.3% in some specific strains. Results of batch experiments using Rhodocyclus gelatinosus, an isolated strain with a superior removal rate of $NH_3--N$ and $NH_3-N$, under the anaerobic condition, showed that the removal rate of organics and $NH_3-N$ was the highest (98.2 and 89.0%, respectively) at the CODcr (mg/L)/biomass (mg/L) ratio of 0.2, and the $NH_3-N$ concentration did not increase with the decreasing $NH_3-N$ concentration. Experimental results from various C/N ratios confirmed that the effective removal rate (75.8%) of $NH_3-N$ occurred even at the low (5:1) C/N ratio as well as high ratios, and the simulataneous removal of $NO_3^--N$ (96.0%).

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.1
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• pp.1-9
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• 2012

This paper explained about the sludge recycling system which retrieved the silicon and abrasive from solar cell wafer slicing. The basic process of the recycling system was multiple centrifuge and secondary processes of ultra sonic agitation, addition of alcohol-water solution and heating sludge was added for raising separation efficiency. The recycling rate was about 96% and 94% for 2N, 4N silicon respectively. The SiC abrasive recycling rate was about 80%. To retrieve the high purity of 4N silicon, the heat process in vacuum furnace was added to remove remaining impurity components.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.167-174
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• 1980

Anionic polymerization of 2-pyrrolidone was carried out via PPBC/KOH catalysis. The effects of PPBC/KOH mole ratio, KOH concentration and temperature on polymerization have been investigated. It was observed that the highest rate of polymerization and maximum conversion were obtained when PPBC/KOH mole ratio was around 0.5. The maximum conversion and the highest viscosity were obtained when the concentration of KOH was 2 mole percent. It was also found that while the rate of polymerization at $50^{\circ}C$ was higher than at $30^{\circ}C$ in the initial stage of polymerization, the conversion and viscosity were decreased as polymerization time was extended. The rate constant $(k_p)$ of polymerization was determined by least square method; the values of $k_p$ obtained were $22.4\;l/mole{\cdot}hr\;at\;30^{\circ}C\;and\;191.9\;l/mole{\cdot}hr\;at\;50^{\circ}C$, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.345-349
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• 2005

Low resistive ($300{\mu}{\Omega}$-cm) W-C-N films have been deposited on tetraethylorthosilicate (TEOS) interlayer dielectric by atomic layer deposition (ALD) with $WF_6-N_2-CH_4$ gas. The exposure cycles of $N_2$ and $CH_4$ are synchronized with pulse plasma. The W-C-N films on TEOS layer follow the ALD mechanism and keep constant deposition rate of 0.2 nm/cycle from 10 to 100 cycles. As a diffusion barrier for Cu interconnection the W-C-N films maintain amorphous phase and Cu inter-diffusion is not occurred even at $800^{\circ}C$ for 30 min.

• Journal of Aquaculture
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• v.6 no.3
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• pp.159-171
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• 1993

The effects of environmental factors (density, light, temperature) and live food on growth and survival rate of zoea and mysis of fleshy shrimp, Penaeus chinensis, were examined. The percent survival rates at the culture densities of 200 and 300 larvae per liter were significantly higher than that of 500 larvae per liter (p< 0.05). The percent survival rates at the culture densities of 100, 200, 300 and 500 larvae per liter were $90.3^{ab},\;95.2^a,\;94.3^a\;and\;86.7^b\%$ (p< 0.05). The effects of light conditions with diatom premix diet showed that continuous light was the best for the survival rate, $96.5\%$. Natural light and continuous darkness showed the survival rates $79.0\%\;and\;4.3\%$, respectively. On the rearing temperature, the survival rates were $97.3\%\;at\;19^{\circ}C\;and\;96.7\%\;at\;22^{\circ}C$ with little difference but the higher temperature resulted in faster growth. The survival rate was $51.6\%;at\;25^{\circ}C$ thus showing significant decrease compared to $19^{\circ}C\;and\;22^{\circ}C$. At this temperature the growth was also suffered. With regard to dietary value of live food, both the best survival rate and the fastest growth were obtained when 6 mixed species of diatom (A. normaii, C. simplex, N closterium, P. tricornutum, S. costatum and T. weissflogii) were provided. When single species was supplied the best survival rate $(82.1\%)$ was obtained with S. costatum, but the other species resulted in much inferior survival rates $(below\;80.0\%)$ and poor growth.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.151-155
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• 2000

We calculated a refractive index of the lens surface by measuring a spectral reflectance for a tinted time on manufacturing of the color lens. The longer a tinted time, the larger a reflectance and reflective index. The refractive index increased for a time up to the colorant's saturation state on the lens surface. The refractive index's change curve of blue color lens for a time depended on the Boltzmann growth curve. then we obtained the parameter's values of $n_{min}=1.482$, $n_{max}=1.497$, $t_c=11.53$ and $d_0=2.287$.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.218-224
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• 2021

This study was conducted to determine the mass-loss rates and the changes in carbon/nitrogen (C/N) ratio of dead woods, which were of following species: Dryobalanops aromatic, D. rappa, and Cratoxylum arborescens. These were dominant tree species in mixed Dipterocarp forests (MDF) and peat swamp forests (PSF) in Brunei Darussalam. In May, 2019, 48 dead wood samples (15 cm×4.8 cm×5 cm) were placed in MDF and PSF sites, and all the samples were collected after 16 months. The effects of species on mass loss were statistically significant (p<0.05); however, no difference was observed in the mass loss obtained from the two forest types (p>0.05). The initial density (g·cm^-3) of the dead woods D. aromatic, D. rappa, and C. arborescens, was 0.64±0.02, 0.60±0.00, and 0.44±0.01, respectively. Also the annual mass loss rate (%) was estimated to be 6.37, 8.17, and 18.53 for D. aromatic, D. rappa, and C. arborescens, respectively. The proportion of dead woods in decay class III was only 25% of C. arborescens samples, which were attacked by wood-feeding invertebrates, such as termites. The C/N ratio decreased significantly in D. aromatic and D. rappa, but the decreasing trend of C/N ratio was not statistically significant in C. arborescens. The results indicate that physical traits of dead woods, such as density, could be one of the main factors causing the decomposition of dead woods initially, as invertebrates such as termites are one of the key decomposers of dead wood in tropical rainforests. In the samples of C. arborescens, which was attacked by invertebrates, nitrogen immobilization occurred to lesser extent as compared to that observed in D. aromatic and D. rappa.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.321-326
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• 2007

An organophosphorus insecticide, chlorpyrifos, has been of a great concern due to persistence, toxicity and accumulation in soils and groundwaters. This study deals with degradation efficiency and dechlorination kinetics of chlorpyrifos by various types of zerovalent irons (ZVIs) for effective remediation of the soils contaminated with chlorinated pesticides. Chlorpyrifos degradation rate was increased with increasing ZVI treatment amount and reaction time. The degradation rate and dechlorination kinetics of chlorpyrifos increased in the order of mZVI > nZVI > cZVI in solutions and soils. Dechlorination number value of chlorpyrifos by cZVI, nZVI and mZVI treatment exhibited 1.08, 3.09 and 3.18, respectively. In soils, degradation efficiency and kinetics of chlorpyrifos significantly were affected by moisture content because of the limited contact between ZVIs and chlorpyrifos. These results suggest that nanosized and functionalized mZVI could be effectively applied to degradation of chlorinated pesticides in the soil and aqueous environments.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.143-143
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• 2017

CrAlN 코팅은 높은 경도, 낮은 표면 조도 등의 상온에서의 우수한 기계적 특성 이외에 고온에서 안정한 합금상의 형성으로 인하여 우수한 내산화성 및 내열성을 보유하여 공구 코팅으로의 적용 가능성이 크다. 그러나 최근 공구사용 환경의 가혹화로 인하여 코팅의 내마모성 및 내열성 등의 물성 향상을 통한 공구의 수명 향상이 필요시 되고 있으며, 다양한 코팅 물질을 활용하여 다층 코팅을 합성함으로써 난삭재용 공구 코팅의 물성을 높이는 연구들이 진행되고 있다. 본 연구에서는 CrAlN 코팅과 WC-Co 6wt.% 모재 사이에 CrZrN, CrN, CrN/CrZrSiN 등의 중간층을 합성하여 CrAlN 코팅의 상온 및 고온 특성을 향상시키는 연구가 진행되었다. 합성된 코팅의 구조 및 물성을 분석하기 위해 field emission scanning electron microscopy(FE-SEM), nano-indentation, atomic force microscopy(AFM) 및 ball-on-disk wear tester를 사용하였다. 코팅의 고온 특성을 확인하기 위해 코팅을 furnace에 넣어 공기중에서 30분 동안 annealing 한 후에 nano-indentation을 사용하여 경도를 측정하였고, $500^{\circ}C$ annealing 코팅의 표면 조도 분석 및 $500^{\circ}C$에서 마찰마모시험을 실시하였다. CrAlN 코팅의 상온 특성을 분석한 결과, 모든 코팅의 경도(35.5-36.2 GPa)와 탄성계수(424.3-429.2 GPa)는 중간층의 종류에 상관없이 비슷한 값을 보인 것으로 확인됐다. 그러나, CrN/CrZrSiN 중간층을 증착한 CrAlN 코팅의 마찰계수는 0.33로 CrZrN 중간층을 증착한 CrAlN 코팅의 마찰계수(0.41)에 비해 향상된 값 보였으며, 코팅의 마모율 및 마모폭도 비슷한 경향을 보인 것으로 보아 코팅의 내마모성이 향상된 것으로 판단된다. 이것은 중간층의 H/E ratio가 코팅의 내마모성에 미치는 영향에 의한 결과로 사료된다. H/E ratio는 파단시의 최대 탄성 변형율로써, 모재/중간층/코팅의 H/E ratio 구배에 따라 코팅 내의 응력의 완화 정도가 변하게 된다. WC 모재 (H/E=0.040)와 CrAlN 코팅(H/E=0.089) 사이에서 CrN, CrZrSiN 중간층의 H/E ratio는 각각 0.076, 0.083 으로 모재/중간층/코팅의 H/E ratio 구배가 점차 증가함을 확인 할 수 있었고, 일정 응력이 지속적으로 가해지면서 진행되는 마모시험중에 CrN과 CrZrSiN 중간층이 WC와 CrAlN 코팅 사이에서 코팅 내부의 응력구배를 완화시키는 역할을 함으로써 CrAlN 코팅의 내마모성이 향상된 것으로 판단된다. 내열성 시험 결과, CrN/CrZrSiN 중간층을 증착한 코팅은 $1,000^{\circ}C$까지 약 28GPa의 높은 경도를 유지한 것으로 확인 되었다. $500^{\circ}C$ annealing 후 진행된 표면 조도와 마모시험 결과, 모든 코팅의 조도 값 및 마찰계수는 상온 값에 비해 증가하였으며 CrN/CrZrSiN 중간층을 증착한 CrAlN 코팅의 변화량이 가장 낮은 값을 보였다. 이는 CrZrSiN 중간층 내에 존재하는 $SiN_x$ 비정질상이 고온 annealing시에 산소 차폐막 역할을 하여, 코팅내의 잔류 산소에 의한 산화작용을 효과적으로 방지함으로써 코팅의 고온 특성이 향상된 것으로 판단된다.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.240-244
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• 2005

본 연구는 시판하는 재리흑돼지육과 개량종 돼지육의 도체성적, 육색, 지방산 조성을 비교함으로서 재래흑돼지육에 대한 기초자료를 제시하고자 실시하였다. 도체성적은 지육중량, 지육율이 재래흑돼지가 낮았으며(p<0.05), 저장기간 동안 $L^*,\;h^{\circ}$ 값은 저장기간 동안 재래흑돼지육이 낮았으며(p<0.05), $a^*,\;b^*,\;C^*$ 값은 저장기간 동안 재래흑돼지육이 높았다(p<0.05). 지방산 조성은 C14: 0, C18:3n6, C18:3n3, C20:5n3, n3 지방산이 재래흑돼지육이 낮았고(p<0.05), n6 지방산과 n3 지방산의 비율은 재래흑돼지육이 높았다(p<0.05). 따라서 이상의 결과를 종합해보면 재래흑돼지육이 개량종 돼지육보다 육색은 우수하였으나 지육중량, 지육율, n3 지방산은 낮았다.