• Journal of Microbiology and Biotechnology
• /
• 제26권11호
• /
• pp.1871-1880
• /
• 2016

Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

• 한국항만경제학회지
• /
• 제23권3호
• /
• pp.29-51
• /
• 2007

Achilleas호 사건은 정기용선계약에서 용선자의 반선지연에 의한 선주의 상실수익과 그 손해배상청구와 관련된 사안이다. 이 사건에서 중재판정부는 정기용선계약상의 반선지연이, (1) 다음의 계약에 대한 지연, (2) 드라이독에 대한 지연, (3) 본선의 매매에 대한 지연 등을 초래할 수 있다고 말하고, 이들이 반선지연에 대한 위험이라는 것을 해운업에 종사하는 자에게는 이미 인식되고 있으며, 또 시장이 항상 변동한다는 것도 알려져 있는 사실이라는 것을 인정하였다. 그리고 손해의 범위가 예상한 것보다 컸다는 사실은 손해배상청구상에 문제가 되지 않으며, 선주가 주장하는 손해의 종류가 추가사항의 체결 시에 당사자에 의한 계약위반으로부터 발생한 것이기 때문에 선주의 주요한 청구는 '통상손해'에 해당한다고 하여 중재인 다수결로 이것을 인정하였다. 이것에 비해 용선자는 지금까지 반선지연에 대해 상실수익이 인정된 선례는 없기 때문에 일반적으로 알려진 손해배상액의 산정기준은 동 원칙의 '통상손해'에 기초하여 반선해야 할 일자로부터 실제로 반선된 일자까지의 시장용선료와 계약용선료와의 차액을 근거로 해야 한다는 것이다. 따라서 상실수익이 손해배상액으로서 인정되기 위해서는 동 원칙의 '특별손해'를 근거로 용선자가 계약체결 시에 스케줄대로 반선하는 것이 중요하다는 취지의 통지를 받고 반선지연에 의한 손해에 대해 책임을 진다는 것을 인식하고 있었던 것이 필요하다고 주장하여 상소하였다. 본 연구에서는 정기용선계약에서 반선지연에 의한 선주의 상실수익과 그 손해배상청구와 관련된 지금까지의 여러 판례를 분석한 후, 특히 Achilleas호 사건 판결내용을 중심으로 그 함축된 의미를 고찰하는데 목적을 두고 있다.

• 한국수정란이식학회지
• /
• 제21권2호
• /
• pp.129-135
• /
• 2006

본 연구는 돼지 체외 수정란의 생산에 있어서 체외성숙 시간이 핵성숙, 다정자 침입율 및 배 발생과 배반포의 부화율 배반포의 부화에 미치는 효과를 검토하였다. 돼지 난포란의 핵성숙율이 체외성숙 36, 38, 40, 42 및 44 시간째에 각각 68.0, 78.0, 79.5, 73.8 및 81.8%로서 각 군간에 유사한 경향이었으며, 체외 수정 후 다정자 침입율도 각각 48.7, 36.0, 44.4, 38.9 및 31.8%로서 차이가 없었다. 체외 성숙 시간에 따른 2세포기 발달율은 체외 성숙 36시간군이 77.3%로서 가장 높았고, 체외 성숙 40 및 44 시간의 70.6 및 70.3%와는 유의차가 인정되었다(p<0.05). 배반포 발달율은 38시간군의 23.1%가 체외 성숙 44 시간군의 15.6%보다 유의하게 높았다(p<0.05). 따라서 돼지 난포란의 44시간 체외 성숙이 배 발생에 비효과적이었다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
• /
• pp.169-174
• /
• 2004

The NOx emission characteristics with oxygen enrichment in nonpremixed counterflow and coflow jet flame of $CH_4$ fuel have been investigated numerically. A small amount of nitrogen is included in oxygen-enriched combustion, in order to consider the inevitable $N_2$ contamination by air infiltration. The results show that the initial increase of NO with increasing oxygen enrichment is due to increasing temperature and residence time, while its subsequent decrease above 75% oxygen is due to decreasing the consumption rate of nitrogen. When oxygen addition exceeds 30%, Thermal NO gradually becomes the dominant production pathway and Prompt NO becomes negative pathway for net NO production rate. It is also seen that Thermal NO plays an important role in NO reduction when strain rate increase in oxygen-enriched combustion. Finally, the results of EINOx with oxygen enrichment in coflow jet flame show the similar profile with those of conterflow flame. It is confirmed that, with leakage of 1% nitrogen in the oxidizer stream, the corresponding EINOx is eight times of that emitted from regular $CH_4$/Air flame.

• Journal of Computing Science and Engineering
• /
• 제2권2호
• /
• pp.200-219
• /
• 2008

The effective management of uncertainty is one of the most fundamental problems in medical decision making. According to the literatures review, most medical decision models rely on point estimates for input parameters. However, it is natural that they should be interested in the relationship between changes in those values and subsequent changes in model output. Therefore, the purpose of this study is to identify the ranges of numerical values for which each option will be most efficient with respect to the input parameters. The Nonhomogeneous Poisson Process(NHPP) was used for describing the behavior of aging chronic diseases. Three kind of failure models (linear, exponential, and power law) were considered, and each of these failure models was studied under the assumptions of unknown scale factor and known aging rate, known scale factor and unknown aging rate, and unknown scale factor and unknown aging rate, respectively. In addition, this study illustrated developed method with an analysis of data from a trial of immunotherapy in the treatment of chronic Granulomatous disease. Finally, the proposed design of Bayesian value of information analysis facilitates the effective use of the computing capability of computers and provides a systematic way to integrate the expert's opinions and the sampling information which will furnish decision makers with valuable support for quality medical decision making.

• 한국재료학회지
• /
• 제15권2호
• /
• pp.85-88
• /
• 2005

[ $W-15wt.\%$ ] Cu nanocomposite powders are fabricated by ball-milling and subsequent hydrogen-reduction. The compacted parts of $W-15wt.\%Cu$ nanocomposite powders were sintered at $1200^{\circ}C$ for 1 h with various heating rates of 5 and $20^{\circ}C/min$. The homogeneity of the sintered microstructures was evaluated through homogeneity index by the standard deviation of Victor's hardness test. The W-W contiguities were calculated by using Voronoi diagrams. The sintered microstructure with the heating rate of $20^{\circ}C/min$ was more homogeneous and had lower W-W contiguity than that of $5^{\circ}C/min$. The microstructural homogeneity was directly related to the W-W contiguity. Thermal conductivity of the sintered parts with the heating rate of $20^{\circ}C/min$ was higher than that with heating rate of $5^{\circ}C/min$. This phenomenon indicates that the thermal conductivity is affected by the W-W contiguity resulting from the homogeneity of the sintered microstructure.

• 한국가축번식학회지
• /
• 제14권3호
• /
• pp.223-230
• /
• 1990

This experiment was carried out to investigate in vitro maturation rate of pig follicular oocytes cultured from 30 to 48hr in TCM 199 supplemented with gonadotropins(FSH, LH) and estradiol-17$\beta$ and in vitro fertilization with ejaculated sperm preincubated in BO medium containing 2mM caffein and development of IVF oocytes. The results obtained in this experiments were as follows ; 1. In addition of hormones, in vitro maturation rate of follicular oocyte increased gradually from 36hr and 74.47% at 48hr in addition of hormones, but there was no differences among in vitro maturation rates after 36hr of culture. 2. Penetration rate of pig oocytes matured in FSH＋LH＋E2 and FSH＋E2 was 71.8%, 71.0% and significantly increased by the addition of hormones. 3. Percentage of developed oocytes was 44.4% for oocytes matured in FSH＋LH＋E2-added medium and 48.7% for oocytes matured in FSH＋E2-added medium, respectively. 4. Two to 16 cells stage embryos were obtained only when pig oocytes matuerd in vitro in hormones-added medium and 72hr after IVF. 5. From present results, it is concluded that gonadotropins and estradiol17$\beta$ can enhance in vitro fertilization and subsequent development as well as in vitro maturation pig follicular oocytes.

• 한국세라믹학회지
• /
• 제43권8호
• /
• pp.472-478
• /
• 2006

The effect of compositional and processing variables on a nitriding reaction of silicon powder compact and subsequent post sintering of RBSN (Reaction-Bonded Silicon Nitride) was investigated. The addition of a nitriding agent enhanced nitridation rate substantially at low temperatures, while the formation of a liquid phase between the nitriding agent and the sintering additives at a high temperature caused a negative catalyst effect resulting in a decreased nitridation rate. A liquid phase formed by solely an additive, however, was found to have no effect on nitridation for the additive amount used in this research. The original site of a decomposing pore former was loosely filled by a reaction product ($Si_3N_4$), which provided a specimen with nitriding gas passage. For SRBSN (Sintered RBSN) specimens of high porosity, only a marginal dimensional change was measured after post sintering. Its engineering implication for near-net shaping ability is discussed.

• 한국패류학회지
• /
• 제22권2호
• /
• pp.151-155
• /
• 2006

Proportion of Tegillarca granosa surviving after 2-6 hrs air exposure with 12 hrs interval at $20^{\circ}C$ and $28^{\circ}C$ for 20 days showed 85-100%, 80-100%, respectively. The survival rate was somewhat lower at high temperature but not significant (p < 0.05). Subsequent exposures for 7-9 days showed survival rate of 8.0-24.1% at $20^{\circ}C$ and $28^{\circ}C$. Oxygen consumption rates and filtration rates were significantly higher for 4 to 6 hrs exposures, compared with the preceding exposures. On the other hand, at $28^{\circ}C$, oxygen consumption rates in adult granular ark for 6 hrs exposure during 20 days had significantly decreased. Filtration rates in study groups increased a little over extended period of exposure, compared with those in control groups, and were similar irrelevant to the time of exposure and size of experimental animals. It is concluded, in view of their viability and oxygen consumption rate during air exposure, that ark shells have quite a high resistance to air exposure with their limited range of responses.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2020년도 가을 학술논문 발표대회
• /
• pp.10-11
• /
• 2020

This research is part of the research for unifying the mass concrete and utilizing the rate of super retarding agent. We analyzed the performance of super retarding agent under low temperature conditions. It was found that there was no deterioration in fluidity and air quality due to the change in the super retarding agent mixing rate. It was found that when super retarding agent was mixed up to 0.5 %, it was delayed for 22.3 hours at 20℃, 48.2 hours at 10℃, and 48.5 hours at 5℃. Therefore in order to ensure the performance required at the site, the super retarding agent mixing rate must be determined by fully considering the situation at the site. In addition it will be analyzed that super retarding agent performance analysis at high temperature will be required in subsequent studies.