• Journal of the Korean Geotechnical Society
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• v.37 no.8
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• pp.5-13
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• 2021

Liquefaction behaviors of two natural silty samples containing fines including clay of 50% or more (Sample No.1 was silt 44.1% and clay 8.8%, sample No.2 was silt 57.2% and clay 12.4%) were examined by a cyclic triaxial test. According to the results on samples containing 50% or more of fine particles, an increase in the fine content decreases the liquefaction resistance of the sample. In other words, when the fine content increases, the liquefaction state of sample is reached with a small number of cyclic loads. In the relationship between the excess pore water pressure ratio and the number of cycles, the slope of the excess pore water pressure ratio increases more steeply as the fine content increases. As a result of analyzing the liquefaction behavior of the two silts with the content of clay contained in the fines, liquefaction occurred more easily in the No.2 silt with high clay content. This result shows that the clay contained in the fines affects the liquefaction behavior of the silt.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.4
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• pp.499-506
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• 2008

The nutritional composition of the white lotus(Nelumbo nucifera Gaertn) leaf are moisture($1.87{\pm}0.06%$), crude ash($9.57{\pm}0.07%$), crude protein($15.53{\pm}0.4%$) and crude lipid($2.42{\pm}0.1%$) per 100g. The highest mineral content was K and Ca. The principal free sugars in the white lotus leaf was sucrose, fructose and glucose. The total phenolics compounds evidenced maximal levels of $8,842.73{\pm}20.57\;g/100g$. DPPH and hydroxyl radical of scavenging ability of each sample tended to increase with increasing degrees of the sample concentration. The $IC_{50}$ values of the ethanol extract, n-hexane, chloroform, ethylacetate, butanol and water fraction from the white lotus leaf to DPPH radicals were 5.65, 8.5, 8.27, 2.03, 2.3 and $13.7\;{\mu}g/mL$ respectively. The $IC_{50}$ values of the hydroxyl radical scavenging ability of the ethanol extract, ethylacetate, butanol and water fraction were 390, 574, 327 and $378\;{\mu}g/mL$ respectively.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1897-1899
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• 2004

In this paper, in order to analyze the characteristics of degradation by salt water with insulation cover and OC wire(outdoor cross-linked polyethylene insulated wire) used in power receiving system, an experimental apparatus has been designed and fabricated. An insulation cover and OC wire were installed in an experimental apparatus, and degraded in each case of 2%, 5%, 10% salinity during 12 weeks. An optical microscope was used to observe a changing process of sample surface, and an electrical safety was analyzed by measuring dielectric breakdown voltages of samples. As salinity increased, so ununiformity of sample surface increased. The breakdown wasn't produced to 50kV about samples regardless of salinity, testing period.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.872-877
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• 2013

In this study, the leakage current - voltage characteristic and leakage current - time characteristic for the undegradated Ethylene Propylene Rubber and the Ethylene Propylene Rubber which is degradated by water tree for 200 hours have been measured on the temperature range of $50{\sim}80^{\circ}C$ and applied DC voltage range of 200 V~800 V for 90 minutes. The results of this study are listed below. In case the temperature is $50^{\circ}C$, it founds that the leakage current have shown a increase in proportion to the applied voltage as 2 pA in 200 V, 6 pA in 400 V, 10 pA in 600 V and 15 pA in 800 V. It founds that the leakage current increased with the rise of temperature. It founds that the leakage current was consistent as time goes by, the leakage current of the sample degradated by water tree for 200 hours has increased more than undegradated sample.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1557-1561
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• 2006

The use of chemically modified silica-salen$(NEt_2)_2$ was studied for the separation and concentration of the metal ions from an aqueous solution by a solid phase extraction. After the salen(NEt2)2 was synthesized, it was chemically bonded to silica gel by a diazonium coupling reaction. The adsorption capacities and binding constants were obtained with respect to Cu(II), Mn(II), Pb(II) and Zn(II) by a graphical method. Some experimental conditions were optimized for the determination of the trace elements. After the silica-salen(NEt2)2 was pulverized in a sample solution of which the pH was adjusted, the solution was stirred to pre-concentrate the metal ions. The metal ions adsorbed were desorbed with nitric acid solution. And the concentrated analytes were determined by a flame AAS. The method proposed here was so rarely influenced by a sample matrix that the procedure was applied to 3 types of water samples. The reproducible results of less than 10% RSD were obtained at the concentration level of ca. 100 ng/mL and the recoveries of 95-109% were obtained in the spiked samples in which given amounts of analytes were added.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.3
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• pp.295-303
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• 2007

Nitrogen compounds in municipal wastewater can be divided into biodegradable and nonbiodegradable fractions with biodegradability. Biodegradable nitrogen compounds can be removed through biological nitrification and denitrification processes, and nonbiodegradable nitrogen compounds affect the effluent quality of biological nutrient removal processes. The amount of nitrifiable nitrogen compounds, which are the sum of ammonia and biodegradable organic nitrogen, has been estimated by respirometry. Respirometry shows good estimation of the concentration of nitrifiable nitrogen when a synthetic sample of ammonium chloride is dosed. The estimated concentration of nitrifiable nitrogen compounds in municipal wastewater is close to ammonia concentration in municipal wastewater, but it is lower than that for the synthetic sample. If nitrogen assimilated into cell synthesis of nitrifiers and heterotrophs is considered, the total amounts of nitrifiable nitrogen compounds, which are nitrified and assimilated, could be more accurately estimated. The concentration of nitrifiable nitrogen compounds, which are biodegradable, is about 31 mg N/l, and this is 119% of ammonia and 94% of total nitrogen. Ammonia, nitrate, biodegradable organic nitrogen, and nonbiodegradable nitrogen are about 79%, 1%, 15%, and 5% of the total nitrogen in municipal wastewater, respectively.

• Preventive Nutrition and Food Science
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• v.15 no.1
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• pp.67-73
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• 2010

The effects of particle sizes (small, medium and large sizes) and gelatinization treatment on the changes of the instant properties of Job's tears powder were investigated. The degree of gelatinization on the different particle size samples of Job's tears powder was the highest in the small particle size, and it also showed an increasing trend regardless of pregelatinizing whether it is or not as the particle size decreased from large particle size to small particle size. The water solubility index of the pregelatinized samples was high compared to that of ungelatinized samples regardless of particle size and temperatures. The water absorption and swelling power increased as particle size and temperature were increased. The dispersibility and sinkability of ungelatinized sample was increased as particle size and temperature were increased and it also showed lower value regardless of particle size and temperature. However, the dispersibility and sinkability of pregelatinized samples were shown to have the opposite result, such that the smallest particle size of pregelatinized sample had the lowest sinkability (11.3%). The turbidity of the pregelatinized small particle size was the highest by a factor of 1.08.

• The Journal of Korean Medicine
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• v.27 no.2 s.66
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• pp.182-195
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• 2006

Objectives : We examined the effect of Hwangryunhaedoktang(HH) on the experimental ulcerative colitis induced by dextran sulfate sodium (DSS). Methods : Experimental colitis was induced in rats by daily treatment with 5% DSS in the drinking water for 5 days. Afterward, the mts were divided into two groups: the control group was administered water and the sample group was administered HH for 7 days. Results : The sample group provided HH for 7 days demonstrated fast recovery of body weight compared with the control group. Histologic change showed fast regeneration of crypt and surface epithelial cells and decreased edema of the submucosa and decreased lymphatic follicle of mucosa compared with the control group. Immunohistochemical stain usingCOX-2 gene was decreased and there was localized Ki-67 positive reaction. Regeneration of surface epithelial cell and goblet cell in mucosa was observed by transmission electron microscope. These results indicate therapeutic effect of HH on DSS-induced colitis in rats.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.4
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• pp.155-167
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• 1996

동일한 하천의 용전산소량(DO)을 예측하는 경우에도 사용하는 재포기계수$(K^2)$는 계산하는 공식에 따라 커다란 차이를 나타매며, 부적합한 공식의 사용에 의한 $(K^2)$의 계산은 하천의 수질관리 정책결정에 지장을 초래하므로 현장사정에 적합한 공식의 개발이 필요하다. 이러한 공식의 개발은 많은 현장측정 자료를 사용하도록 신뢰성이 높으나 현장측정은 소요되는 비용에 제약을 받기 때문에 신뢰성과 경제성을 동시에 고려한 표본의 크기의 적정규모를 산정하는 것이 필요하다. 본 연구에서는 Monte Carlo 방법에 의해 통계적으로 수출된 $(K^2)$를 사용해서, 주어진 자료에 의해 개발된 공식을 사용할 때 야기되는 오차가 $(K^2)$개수의 증가에 따라 얼마나 감소하는지를 널리 사용되는 공식 중에 Owen공식과 Churchill공식을 New Jersey에 있는 Passaic River에 적용시켜 검토하였다. 표본의 크기가 10에서 20으로 증가할 때 오차가 크게 감소하였으며 20을 넘어 증가시켰을 때에는 오차의 감소폭이 미미하였다. 초차의 감호형태와 단위측정당 소요되는 비용을 고려할 때 약 20정도의 표본의 크기가 적정수준의 규모에 판단된다. 이러한 적용사례의 결과는 회귀모델의 이론적 계산결과에 의한 오차 감소와 흡사하여 본 연구결과는 여러 가지(K2)공식과 광범위한 하천의 조건에 적용이 가능할 것이며, 본 연구에서 사용한 적정표본의 크기 산정방법은 회귀분석에 의해 실험식을 개발하는 다른 분야에도 적용이 가능하다.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.295-302
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• 2000

Earthquakes not only produce additional load on the structures and underlying soil, but also change the strength characteristics of the soil. Therefore, in order to analyze soil structures for stability, the behaviour after earthquake must be considered. In this paper, a series of cyclic triaxial tests and monotonic triaxial tests were carried out to investigate the undrained shear strength and liquefaction strength characteristics of Nak-Dong River sand soils which were subjected to cyclic loading. The sample was consolidated in the first stage and then subjected to stress controlled cyclic loading with 0.1Hz. After the cyclic loading, the cyclic-induced excess pore water pressure was dissipated by opening the drainage valve and the sample was reconsolidated to the initial effective mean principal stress(p/sub c/'). After reconsolidation, the monotonic loading or cyclic loading were applied to the specimen. In the results, the undrained shear strength and liquefaction strength characteristics depended on the pore pressure ratio(Ur=U/p/sub c/'). The volume change following reconsolidation can be a function of cyclic-induced excess pore water pressure and the maximum double amplitude of axial strain.