• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.23-24
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• 1999

분진은 그 안에 Pb, Cr, Cd, Zn등 각종 중금속 및 유해물질을 함유하고 있으며(Jaenicke, R., 1988), 이러한 조성은 분진의 발생원과 밀접한 관련이 있다. 또한, 분진의 물리, 화학적 특징들은 대기로의 배출정도나 화학적 변형 외에도 기상학적 인자들에 의해 영향을 받는다(Karakas와 Tuncel, 1997). 이러한 분진들은 최종적으로 지상에 낙하할때의 분진으로서 비교적 크기가 큰 강하분진과, 입자가 미세하고 가벼워서 좀처럼 침강하기 어려워 장기간 대기중에 떠 다니는 부유분진으로 나눌수 있으며, 이 중 강하분진은 대기중의 오염물질 중 자기 중량에 의해 또는 우적에 포함되어 침강하는 매연 및 분진과 그 외 불순물로서, 그 측정치는 일정지역에 있어서의 오염변동을 나타내고 지역적 비교의 지표로서 이용되고 있다(김은경등, 1996)(중략)

• Journal of the Korean GEO-environmental Society
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• v.3 no.2
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• pp.49-60
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• 2002

A study on mineral composition and chemical component governing of weathering process is necessary to know the weathering characteristics of sedimentary rocks. In this study, a mineral and chemical component analysis, and physical and engineering characteristic tests were conducted to find out the characteristics of sedimentary rocks in Daegu, according to the weathering degree of sedimentary rock. Test results show that the mineral composition of rock, such as Albite (Ab), Muscovite (Ms), Magenetite (Mt) and the chemical composition of $A_2O_3$, CaO, $Na_2O$, $K_2O$, MgO and so on are closely related to the weathering. Based on the test results, we illustrated the quantitative application of weathering decision for the sedimentary rocks.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.664-671
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• 2011

The vacuum residue of petroleum refinery, i.e. asphalt, was modified through a non-catalytic air blowing process to prepare the semi-blown asphalt. Changes in composition, chemical structure, and physical properties of asphalt were examined. The result from the thin layer chromatography showed that the asphaltene content in asphalt was increased by the air blowing on account of the aromatization of aliphatic hydrocarbon and condensation. These changes in molecular structure were also confirmed by $^1H-NMR$, differential scanning calorimetry, and thermogravimetry. Because of the molecular structure changes, the penetration of asphalt was decreased and the softening point and the flash point of asphalt were increased.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06b
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• pp.38-46
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• 1995

Bonded film을 형성시키기 위한 대표적인 고체윤활제들로는 이황화-몰리브데늄, 이황화-텅스텐(WS$_{2}$), 보론-나이트라이드(BN), 흑연(Graphite) 등을 들 수 있으며, 이들 고체윤활제를 표면에 효과적으로 부착시키기 위하여 사용되는 수지류는 페놀 및 에폭시계수지 등이 사용되고 있아. Bonded film의 마찰마모특성은 이와 간이 피막 내에 첨가된 고체윤활제 및 수지의 종류, 고체윤활 입자들의 크기 및 순도,그리고 이들 상호간의 배합비율 등에 의하여 크게 좌우되며, 아울러 피막 내에 소량으로 첨가될 수 있는 여러 가지 보조첨가제들에 의해서도 크게 영향을 받는 것으로 알려져 있다. 고체윤활제 성분들의 조성과 더불어, 재료표면의 물리화학적인 전처리 조건도 매우 중요한 요인이 될 수 있다. 따라서 본 논문에서는 이와 같은 윤활피막내 고체윤활제들의 배합, 고체윤활피막의 표면전처리 방법들을 변화하고 이들에 따른 상기 고체윤활피막들의 마찰 및 마모 특성에 관하여 시험을 행하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.71-72
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• 2011

최근 스마트 휴대폰으로 대표되는 이동통신기기 산업의 빠른 성장으로 인하여 이들 기기를 보호하기 위한 표면 처리기술이 함께 발전하고 있다. 그중 대표적인 것이 나노기술을 융합한 보호막 도장 기술이다. 본 연구에서는 마그네슘 기판과 플라스틱 케이스 소재 위에 유무기 하이브리드 도장막을 형성시키고, 도장막의 실리카 조성에 따른 물리화학적 변화 거동을 관찰하였다. 특히, 실리카 나노입자가 첨가된 실리카 졸 용액과 UV 경화수지를 다른 비율로 혼합한 나노형 하이브리드 코팅용액을 사용하였으며, 딥 코팅과 스프레이 코팅법을 개별적으로 이용하여 형성한 유무기 하이브리드 코팅층의 경도와 내지문 특성을 중점적으로 조사하였다. 이러한 연구를 통하여 유무기 하이브리드 코팅층 형성에서 실리카 졸의 역할과 최적 물성확보를 위한 근거를 마련하였다.

• Clean Technology
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• v.19 no.2
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• pp.148-155
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• 2013

Volatile fatty acids (VFAs) production from marine brown algae, Saccharina japonica, was investigated in anaerobic dark fermentation. In order to evaluate the VFAs productivity, various experimental parameters (i.e., physicochemical pre-treatment, microorganism inoculation ratio, substrate concentration, and pH) were evaluated. According to the physicochemical pre-treatment methods, the maximum concentrations of VFAs were obtained in the order of sulfuric acid, subcritical water and subcritical water with lipid-extraction. Also, we investigated the operating parameters such as microorganism inoculation ratio (MV/M = 10 to 30), the substrate concentration (18.0 to 72.0 g/L) and pH (6.0 to 7.0) in sulfuric acid pre-treatment method. When the substrate concentrations were 18.0, 36.0, 54.0 and 72.0 g/L at $35^{\circ}C$, microorganism inoculation ratio 15, pH 7.0 for 372 hours, the maximum concentrations of VFAs were respectively 9.8, 13.9, 18.6 and 22.3 g/L. The change in VFAs concentrations was detected that acetic- and propionic acids increased according to increasing pH, while the butyric acid increased with decreasing pH. The VFAs obtained from concentration and separation process may be used as basic chemistry materials and bio-fuel, and they will expect to produce alternative energy of fossil fuel.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.2
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• pp.101-111
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• 2009

In this study, the physico-chemical characteristics of municipal solid waste (MWS) which was treated in gangwon area were investigated. It is necessary to measure the characteristics of municipal solid waste for build a waste treatment and RDF facility and for data-base and total managing of the landfill. It was found that the average density of solid wastes is in the range of $101.8{\sim}199.8kg/m^3$. This MSW was composed of 30.7% of food wastes, 36.3% of papers, 15.8% of plastics & vinyls, 1.9% of textiles, 3.2% of wood and 1.5% of rubber & leathers respectively. Most of MSW are composed of food, paper and plastic waste and the combustible waste is more than 90%. For three components, moisture is 44.6%, combustible component is 47.7% and ash is 7.7% respectively. The chemical elements are carbon, oxygen, and hydrogen on the dry basis of wastes. The low heating value of the MSW measured by calorimeter was obtained as 2,631 kcal/kg, and the high heating value of the MSW was obtained as 3,310 kcal/kg.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.70-78
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• 2008

In this study, the composition and physico-chemical characteristics of school waste which is located in B area, kyunggi-do was investigated. It is necessary to measure the characteristics of school waste to build the data-base for resource and recycling of waste. This school waste was composed of 12.25% of food wastes, 56.26% of papers, 9.26% of plastics&vinyls, 1.52% of textiles, 3.70% of wood, 0.11% of rubbers&leathers and others, respectively. Most of school wastes are mainly composed of paper and plastic waste and composition of combustible waste was about as 90%. From 3-components analysis, contents of moisture, combustible component, and ash was 5.72%, 88.29% and 5.98%, respectively. Moisture content was higher in Agricultural Dwelling school area compare to the urban dwelling school area. The chemical element of the school waste has the high order of carbon, oxygen, hydrogen on the dry basis of wastes and the low heating value of the MSW which is measured by calorimeter is shown as 3720.44kcal/kg.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.99-104
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• 2024

In this study, a carbon coated hollow silicon (HSi/C) composite material was prepared for anode material of high-capacity lithiun-ion battery. Hollow silica (HSiO₂) was synthesized by the Stöber method with CTAB (N-Cetyltrimethylammonium bromide). The HSi/C anode composite was manufactured by carbon coating after magnesiothermic reduction of HSiO₂. The physical and electrochemical characteristics of the prepared anode materials were investigated based on CTAB amount. In the FE-SEM analysis, it was found that the HSiO₂ particle size increased as CTAB amount decreased, but shell thickness decreased. The HSi/C composites exhibited high initial discharge capacities of 1866.7, 2164.5 and 2188.6 mAh/g with various CTAB ratios (0.5, 1.0, 1.5), respectively. After 100 cycles of charge-discharge, 0.5-HSi/C demonstrated a high reversible capacity of 1171.3 mAh/g and a capacity retention of 70.9%. Electrochemical impedance spectroscopy (EIS) was employed to analyze the impedance characteristics, and it revealed that 0.5-HSi/C showed more stable resistance characteristics than HSi/C composites with other CTAB amount over 20 cycles.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.160-189
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• 2023

The Cheonjeon-ri petroglyph is inscribed with shale formation belonging to the Daegu Formation of the Gyeongsang Supergroup in the Cretaceous of the Mesozoic Era. This rock undergoes thermal alteration to become hornfels, and has a high hardness and dense texture. Rock-forming minerals have almost the same composition as quartz, alkali felspar, plagioclase, calcite, mica, chlorite and opaque minerals, but calcite is rarely detected in the weathered zone. The petroglyph forms a weathered zone with a certain depth, and there is a difference in mineral and chemical composition between weathered and unweathered zones, respectively. The CaO contents of the weathered zone were reduced by more than 90% compared to that of the unweathered zone, because calcite reacted with water and dissolved. As a result of calculating the surface weathering depth for the petroglyph with the transmission characteristics of X-rays, depth of the parts in falling off and exfoliation showed a depth of about 0.5 to 1 mm, but the weathering depth in most areas was calculated to be about 3 to 4 mm. This can be proved by the contents and changes of Ca and Sr. The surface discolorations of the petroglyph are distributed with different color density, and the yellowish brown discoloration is alternated with a thin biofilm layer, showing a coverage of 79.6%. Therefore, periodic preservation managements and preventive conservation monitoring that can effectively control the physicochemical and biological damages of the Cheonjeonri petroglyph will be necessary.