• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.121-127
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• 2011

In this study, possible use of indigenous natural loess (Hwangtoh) as a new binding material via geopolymerization process is examined. Hwangtoh pastes with four different mix proportions of varying alkali liquid concentrations (6 M, 8 M) and the constituents of the binder as well as the alkali liquid at a constant liquid-to-binder ratio of 0.55 were prepared. Analysis of the natural loess (Hwangtoh) paste was carried out as follows : 1) Measurement of compressive strength and weight of cubic specimens versus curing time; 2) Analysis by X-ray diffraction (XRD) and scanning electron microscope (SEM) about reaction product; 3) Porosity analysis of hardened Hwangtoh paste. The result showed that it is possible to prepare Hwangtoh paste with 29.1 MPa at the age of 7 day by using alkali solution (made as 1 : 4.5 the mass ratio of liquefied $Na_2SiO_3$ and NaOH solution and applying the curing temperature of $60^{\circ}C$). Compressive strength development with respect to the degree of moisture evaporation from the paste seems to be independent of curing temperature. Therefore, it seems that higher early strength of the paste specimens cured at higher temperature can be attributed to both higher rate of reaction and moisture evaporation.

• Journal of the Korean Geographical Society
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• v.48 no.2
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• pp.167-183
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• 2013

This paper aimed to investigate the Asian dust source region and climatic condition of source region by the case of Asian dust in south Korea. In order to analyze the weather condition of source region, observed the Asian dust days data and weather data in China were used. The Asian dust days originating from inner-Mongolia were the most frequent. The Asian dust days originating from all the source regions except Loess plateau were increased recently and occurred over the country. In case of Loess plateau, the frequency of the Asian dust days in 1960s was the highest and only the southern region of the south Korea was mostly affected. The relationship between the Asian dust days of Korea and climatic factors of spring and April of source region was significant. The relationship between the Asian dust days originating from the inner Mongolia and sea level pressure of April and relative humidity of spring was negative. The Asian dust days from Gobi had positive relationship with wind gust days and negative relationship with sea level pressure in April. The Asian dust days from Manchuria had negative relationship with precipitation and sea level pressure in April. The Asian dust days from Loess plateau had positive relationship with maximum wind speed and negative relationship with sea level pressure in April.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.309-310
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• 1999

Loess (黃土)는 지구의 10 ％를 차지하고 있으며, 황사 (黃砂)폭풍으로 장거리이동이 가능하여 동아시아까지 이동할 수 있다 (Zhang De'er, 1982). 황사현상은 최근 동북아시아에서 급속한 산업발달과 인구증가, 그리고 생활수준의 향상에 따라 많은 양의 오염물질이 대기로 방출되고 있다. 특히 중국이 이 지역에서 배출되는 대기오염물질의 대부분을 배출하고 있다 (국립환경 연구원, 1998).(중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.143-144
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• 2000

자연황토를 해수와 혼합 분쇄, 적조발생 해역에 정확히 살포하여 보다 경제적으로 황토를 살포하는 황토살포기 및 황토가 pH값의 변화에 따라 활성도가 달라지는 연구결과에 착안하여 해수를 전기분해하여 생성되는 전해수(산성수 및 알칼리수)에 황토를 혼합하여 황토를 활성화시켜 적조구제효율을 높이는 방법에 대하여 연구를 실시, 보다 효율적이며 친환경적인 적조구제 기술을 개발하였다. (중략)

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.95-98
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• 2003

Polymeric composite materials on the basis of some industrial wastes are obtained. Some physical parameters of experimental samples are determined. The analysis of exploitative properties of these polymer composite materials allows recommending them as a heat-insulating material in constructions.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.159-160
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• 2002

Soil dust particles transported from loess regions of the Asian continent, called Asian dust, highly influences the air quality of north-eastern Asia and the northern Pacific Ocean. The effects of these dust storms, on the chemical composition of atmospheric aerosol particles with different size, was investigated. Measurements of size distributions of total aerosol and major ion species were carried out on Jeju Island, Korea. (omitted)

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.247-248
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• 2003

최근 환경과 건강에 대한 관심이 증대되면서, 염색 가공분야에 있어서도 환경오염을 일으키지 않으면서도 위생적인 쾌적성을 부여하는 가공이 큰 주목을 받고 있다 이러한 측면에서 황토와 키토산은 두 가지 요구를 모두 충족시킬 수 있는 훌륭한 천연소재이다. 본 연구에서는 황토 염색 전, 후에 키토산을 처리한 면직물을 이용하여, 키토산의 농도와 처리 조건에 따른 항균성 중진효과를 고찰하고자 하였다. (중략)

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.325-331
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• 2006

Various environmental conditions affecting total phosphorus removal from farm wastewater in a biofilm filter process were investigated using loess balls and Chromobacterium LEE-38 at a pilot plant. When Chromobacterium LEE-38 was used, the removal efficiency of total phosphorous was approximately 10- or 5-fold higher than that of Acinetobacter CHA-2-14 or Acinetobacter CHA-4-5, respectively. When a loess ball of $11{\sim}14mm$ manufactured at a $960^{\circ}C$ calcining temperature was used, the removal efficiency of total phosphorous was 90.0%. When 70% of the volume fraction was used, the maximum efficiency of total phosphorus removal was 93.1%. Notably, when the initial pH was in the range of 6.0 to 8.0, the maximum removal efficiency of total phosphorus was obtained after 30 days. When the operating temperature was in the range of 30 to $55^{\circ}C$, the maximum removal efficiencies of total phosphorus, 95.6 to 94.6%, were obtained. On the other hand, at operating temperatures below $20^{\circ}C$ or above $40^{\circ}C$, the removal efficiency of total phosphorous decreased. Among the various processes, biofilm filter process A gave the highest removal efficiency of 96.4%. Pilot tests of total phosphorus removal using farm wastewater from the biofilm filter process A were carried out for 60 days under optimal conditions. When Acinetobacter sp. Lee-11 was used, the average removal efficiency in the p-adsorption area was only 32.5%, and the removal efficiencies of chemical oxygen demand (COD) and biological oxygen demand (BOD) were 56.7 and 62.5%, respectively. On the other hand, when Chromobacterium LEE-38 was used, the average removal efficiency was 95.1%, and the removal efficiencies of COD and BOD were 91.3 and 93.2%, respectively.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.343-347
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• 2003

Power of loess ball on nitrogen and phosphorous removal in wastewater treatment were investigated. flow line A ( anaerobic${\rightarrow}$oxic${\rightarrow}$anoxic(organic source methanol)${\rightarrow}$p-absorption) showed the results of T-P 0.5, T-N 1.0, and COD 10ppm bellow, and flow line B ( oxic${\rightarrow}$anoxic, organic source: methanol${\rightarrow}$p-absorption) showed the results of T-P 0.3, T-N 5.0, and COD 15 ppm bellow. flow line C ( anaerobic${\rightarrow}$oxic${\rightarrow}$anoxic, organic source: wastewater ${\rightarrow}$ p-absorption) showed the results of T-P 0.6, T-N 10, and COD 15 ppm bellow, and flow line D ( oxic${\rightarrow}$anoxic, organic source: methanol${\rightarrow}$p-absorption) showed the results of T-P 1, T-N 8m, and COD 20 ppm bellow. So the results of these experiments showed the probability of loess ball in wastewater treatment.

• Analytical Science and Technology
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• v.30 no.4
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• pp.182-193
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• 2017

In order to examine the variation characteristics of chemical compositions in relation to the inflow pathways of Asian dust, $PM_{10}$ and $PM_{2.5}$ aerosols were collected at Gosan site of Jeju Island during the Asian dust days between 2010 and 2015, and their chemical compositions were analyzed. The mean mass concentrations of $PM_{10}$ and $PM_{2.5}$ during Asian dust days were $130.0{\pm}90.2$ and $38.2{\pm}24.7{\mu}g/m^3$, respectively. The composition ratios of major secondary pollutants ($nss-SO_4{^{2-}}$, $NH_4{^+}$, $NO_3{^-}$) were high as 53.7 % for $PM_{10-2.5}$ and 90.6 % for $PM_{2.5}$. When the Asian dusts had been transported to the Korean Peninsula via Loess Plateau of central China, the concentrations of $nss-Ca^{2+}$, $NH_4{^+}$, $nss-SO_4{^{2-}}$, and $NO_3{^-}$ increased more noticeably. Whereas in case when the inflow pathways of Asian dust had been through the Bohai bay, the concentrations of the crustal species such as Al, Fe, and Ca were relatively high in coarse particles. The atmospheric aerosols were acidified largely by sulfuric and nitric acids. They were neutralized mainly by calcium carbonate in coarse particle mode passed through Manchuria area, but by ammonia in fine particle mode passed through Loess plateau and Bohai bay. Ammonium salts are assumed to exist as ammonium sulfate and ammonium nitrate in coarse particles, but mostly as ammonium sulfate in fine particles.