• Journal of the Mineralogical Society of Korea
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• v.28 no.2
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• pp.147-163
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• 2015

Chemical and mineralogical properties of coal ash samples from the nine thermal power plants of Korea were investigated to acquire basic data for estimating the potential of rare metal recovery. Chemical compositions of coal ash were consistent with those of average shale and foreign coal ashes. However, there were small differences between the metal contents of domestic anthracitic and imported bituminous coal ashes. Unburned coal particles were much abundant in the ash of domestic anthracitic coal. Chalcophile elements were relatively enriched in the fly ash compared to bottom ash. Silicate glass was the major component of coal ash with minor minerals such as quartz, illite (muscovite), mullite, magnetite, lime, and anhydrite. Al and Si were the major components of the glass with varying contents of Ca, Fe, K, and Mg. Glass occurred in a form of porous sphere and irregular pumace-like grain often fused with iron oxide spheres or other glass grains. Iron oxide spheres were fine intergrowth of fast-grown iron oxide crystals in the matrix of silicate glass. Chemical, microstructural, and mineralogical properties would guide successful rare metal recovery from coal ash.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.201-207
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• 2009

The hydrogenation reaction of methyl dodecanoate for the synthesis of 1-dodecanol has been carried out in the presence of a copper chromite catalyst. The catalysts were synthesized by ceramic method, co-precipitation, and improved co-precipitation method and the particles were characterized by SEM and XRD. Also, the products of the reaction were assigned by GC, GC/MSD and NMR. The particles synthesized by each method showed (1) a spherical shape with the size of 3.2 to $7.0{\mu}m$, (2) an agglomerated spherical shape with the size of 50 to 500 nm and (3) a spherical shape with smaller particle size, respectively. Especially, in order to control the size of particles, the particles were synthesized in various dispersant solutions as Span 80, polyacrylate, and polyethyleneglycols (PEGs). The particles synthesized in PEG (Mw = 4000) solution showed the smallest particle size of 30 to 50 nm and the regularity of the particle size distribution. Our experimental results elucidated that the activity of catalyst for hydrogenation increases with decreasing the size of catalyst particle. The highest yield of dodecanol in the hydrogenation reaction was 95.5% when copper chromite synthesized in the PEG solution was used as a catalyst in the optimized reaction condition.

• Food Science of Animal Resources
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• v.28 no.5
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• pp.549-554
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• 2008

Liposomes were prepared from egg yolk phospholipids to study their physical properties and stability at various storage conditions. Under storage conditions at different pH levels, the particle sizes of liposomes increased at the range of pH 1-2, and the absolute values of $\xi$-potentials were reduced at the range of pH 1-4. The leakage of sulforhodamine B (SRB), a fluorescent dye which is encapsulated in the liposome, increased greatly at pH 2-4. At different storage temperatures, the particle size of liposomes increased from the 10 days of storage at $4^{\circ}C$ and the 40 days at 20 and $35^{\circ}C$. The $\xi$-potentials decreased slightly later during storage under 4, 20 and $35^{\circ}C$. At the storage temperature of $50^{\circ}C$, the leakage of SRB was the greatest. Therefore, we concluded that the pH conditions lower than pH 6 and high temperature of $50^{\circ}C$ are not conducive to storing liposomes. The results obtained here may prove helpful in developing liposome-based encapsulation and diagnostic reagents.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.190-204
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• 2010

This study firstly examined the socioeconomic and health factors associated with infiltration of private health insurance. Secondly, we compared health behavior, outpatient and inpatient use of private health insured with uninsured. The method of this study is that secondary analysis of the 2008 Korea National Health and Nutrition Survey was conducted for 7178 respondents aged 19 over. We use the logistic regression and t-test for data analysis. The first dependent variable was dichotomy which is divided to private health insured or uninsured and the second dependent variable was the presence and frequency of outpatient and inpatient use. The descriptive variables was gender, age, marital status, income, education, occupation, type of national health insurance, residential area, self confidence of health, prevalence rate of common disease, activity limitation, drinking and smoking status. The result of the major findings are as follows. First, 59 under aged person, married person, people in the higher brackets of income, national employee insured were more likely to infiltrate private health insurance. The poor self confidence of health, activity limitation, person with hypertension or allergic rhinitis and smoker were negatively related in infiltrating private health insurance. Second, private health insured did more preventive behavior such as self-paid health examination, cancer screening, regular exercise than uninsured. Third, private health insured was positively related with the presence of outpatient use and frequency of inpatient use

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.146-154
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• 2002

To assess the adsorption and removal mechanism of dissolved inorganic nutrients in seawater by scattering yellow loess, a laboratory experiment was conducted for the change of nutrient concentration in seawater during the course of time depending on particle size and scattered concentration of the yellow loess. Twenty four hours after the addition of yellow loess in the size range of 0 $\mu$m to 500 $\mu$m in seawater, the removal rate of dissolved inorganic phosphorus (DIP) was increased with increasing amount of yellow loess. There was little difference among the removal rates depending on the size of yellow loess. On average, $26\%$ of dissolved inorganic silicate was reduced for the same period. No greate difference among the removal rate depending on both size and amount of yellow loess was found. Our results suggested that the removal mechanism of DU seemed to be associated with mostly the chemical bond with iron. More than $99\%$ of initial DU concentration was likely to be removed by this mechanism. In the case of inorganic dissolved silicate, the removal mechanism was likely to be attributed to a cation exchange between the yellow loess and seawater.

• Journal of the Microelectronics and Packaging Society
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• v.4 no.1
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• pp.1-12
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• 1997

본 연구에서는 용액성장법에 의해 양자 입자로 구성된 CdS 박막을 슬라이드 유리기 판위에 성장시키고 이들의 구조적 광학적 특성에 대하여 연구하였고 이들 결과를 토대로 용 액성장법으로 성장된 CdS 박막의 양자 사이즈 효과에 대하여 연구하였다. 성장시간은 1, 3, 10, 20분이었고 성장온도는 75$^{\circ}C$였다. X-선 회절 분석결과 본 연구에서 합성된 CdS 박막은 hexagonal상의 결정구조를 갖는 것으로 나타났고 성장시간에 따라 막의 투께는 61~195nm, 입자사이즈는 8.5~22.5nm로 나타났다. 광에너지 변화에 따른 투과도 측정결과 본 연구의 CdS 시료는 성장시간에 따라 에너지 밴드갭이 2.43~2.51 eV로 나타나서 벌크 CdS의 에너 지 밴드갭인 2.42 ev보다 높은 에너지 밴드갭을 갖게 되어 양자 사이즈 효과에 의한 blue shift 현상이 용액성장법에 의해 합성된 CdS 시료에도 존재한다는 것이 밝혀졌다 그리고 이 같은 용액성장법으로 성장된 CdS에 대해 최초로 수행된 Raman 산란 실험결과 이성장방법 으로 성장된 CdS에는 1TO, E2, 1LO 포논 모드가 존재함을 알수 있었고 또한 입자 사이즈 감소에 의한 1LO포논 모드의저주파수 shift 현상 즉 포논 모드의 softening 현상이 있음이 밝혀졌고 softening은 최대6.2%까지 발생하였다. 이와같은 높은 softening은 본연구의 CdS 박막 내 양자 입자의 입도가 작은것에 기인하는 것으로 밝혀졌다. 또한 본 CdS 시료의 양 자 사이즈 효과의 결과로 1TO 포논도 나타났는데 이 1TO 포논과 E2 포논의 Raman shift 는 성장시간 즉 막의 두께와는 무관한 것으로 나타났다.행렬모형(二重比例行列模型)을 이용하여, 산업구조의 변화로 인한 직업별 인력수요 변화가 충분히 고려되도록 하였다. 전망의 결과에 따르면 향후 우리 경제는 지식기반경제(knowledge-based economy)로 이행하고 있다고 볼 수 있다. 우선 산업구조면에서 지식집약적산업으로의 구조조정이 일어나게 되고 이에 따라 산업별 취업구조에서도 고기술산업의 취업준비중이 급속히 증가하게 된다. 직업별 취업분포에 있어서도 전문기술직 행정관리직 등의 고숙련 사무직의 비중은 크게 증가하는 반면 생산관련직과 농림어업직의 비중은 감소하게 된다. 이처럼 경제가 지식집약화되어 감에 따라 고학력자에 대한 수요는 지속적으로 증가하지만 현재 적절한 인력양성과 공급이 이루어지지 않고 있어 향후 기술이나 기능에 따른 수급부일정(需給不一政)(skill mismatch)현상이 매우 심해질 것으로 보인다. 따라서 앞으로의 인력정책에서 가장 주안점을 두어야 할 부분은 첨단기술산업과 관련된 인력의 양성에 있다고 하겠다.2시간까지 LPDG용액은 MEC용액보다 비교적 나은 회복을 보였고 재관류 3일과 7일의 폐기능 평가에서 두 용액 모두에서 폐기능의 점차적 소실을 보였으며 이는 병리조직검사에서 보듯이 폐혐에 의한 외적인 요소라고 생각되며 따라서 LPDG용액은 허혈재관류손상 방지 및 급성폐렴 등 염증을 잘 관리한다면 20시간 이상 LPDG용액의 안전한 폐보존의 가능성 을 얻을 수 있었다.ic 형태로 외래유전자가 발현되었지만 대조구에서 87.0% (26/30개) 배반포기가 $\beta$-Gal 활력을 보인 반면, G418 처리구에서는 모든 배반포기가 $\beta$-Gal 활력을 보였다 (P<0.05). 그러나 대조구 및 G418 처리구의 ICM

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.165-166
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• 2014

The application of particle reaction model in the packed bed process modeling is discussed for iron ore pellet induration process. Combustion of coke breeze in the pellet is estimated by using shrinking unreacted-core model and grain model in which the progress of chemical reaction is described in different concepts. Under the identical inlet gas and solid conditions, the calculation using shrinking core model showed deviated results in terms of temperature profile and conversion fraction, which may imply the significance of selecting proper particle reaction model in consideration of particle characteristics and process operation conditions.

• Journal of Environmental Science International
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• v.15 no.12
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• pp.1171-1175
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• 2006

Deposited road particles (DRPs) were analysed for heavy metal concentrations at four different roads in a city, Korea. The samples were collected using a roadway surface vacuum cleaning vehicle which was commonly used in collecting roadway surface particles. Six particle size ranges were analyzed separately for twelve heavy metal elements (Cd, Cr, Pb, Ni, Al, As, Co, Cu, Fe, Mn, Zn and Hg). At all sampling sites, the high concentration of the heavy metals occurred in the <74um particle size range, which conventional roadway cleaning vehicles do not remove efficiently. The Pb concentration significantly increased with decreasing particle size of DRPs, and other toxic heavy metals (Cd, Cr and Ni) also showed similar results. The heavy metal concentrations in the smaller size fraction of DRPs is important because they are contaminants that are preferentially transported by road runoff during rainfall.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.255-256
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• 2003

강수의 대표적인 산성 오염물질은 주로 화석연료의 연소 과정에서 발생하는 황산화물과 질소산화물이며 이들을 강한 산성물질로 전환시키는 과정에서 오존, 과산화수소, 과산화물, 탄화수소 등이 크게 기여하고 있다. 이외에도 유기산, MSA 등이 강수의 산성화에 기여하고 있으나 이들의 기여도는 대체적으로 황산화물과 질소산화물에 비해 비교적 낮다. 반면에 암모니아나 토양의 칼슘화합물 등의 염기성 물질들은 강우의 산성 물질을 중화시키는 역할을 하는 것으로 조사되고 있다. 특히 토양입자에 의한 중화과정은 최근 빈번해진 황사의 영향 때문에 조사의 필요성이 크게 부각되고 있다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.371-372
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• 2003

서울의 지하철은 하루 450만 명 정도를 수송하는 중요한 대중교통 수단이다. 지하철 역사 내의 실내 환경에 대한 실내공기질 관리는 실내공기 오염의 대상물질에 대한 특정유해물질과 같은 단일 물질에 대한 지표에 의해 관리되고 있다. 그러나 공기중 입자상 물질의 특성은 복합적이기 때문에 공기질에 대한 관리는 여러 제한점을 가지고 있다. 또한 역구내의 먼지에 대한 단순 측정ㆍ분석만이 이뤄지고 있을 뿐 그 먼지의 생물학적 영향에 대한 연구는 미흡한 실정이다 본 연구에서는 지하철역 구내에서 포집한 미세먼지가 돌연변이원을 함유하고 있는 지를 여름과 겨울철에 대한 비교 평가하였다. (중략)