• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.569-572
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• 2007

천연가스의 주요 구성성분은 메탄, 에탄, 프로판으로 99%이상 차지하고 있으며 천연가스 하이드레이트(NGH)는 압축천연가스(CNG)에 비해 체적당 질량이 크고 액화천연가스(LNG) 보다 상대적으로 유리한 온도 및 압력조건으로 인해 천연가스의 경제적인 저장 및 수송 수단으로 주목 받고 있다. $CH_4$ - $C_2H_6$, $CH_4$ - $C_3H_8$ 혼합가스 하이드레이트의 제조시 반응시간에 따른 하이드레이트의 거동을 관찰하였으며 생성조건의 변화에 따른 하이드레이트의 생성속도를 비교하였다. 하이드레이트의 생성이 진행될 때 기상에서의 $C_2H_6$, $C_3H_8$의 몰 비는 감소함을 보여주었고 이러한 변화는 $CH_4$ - $C_3H_8$가 $CH_4$ - $C_2H_6$보다 더욱 빠르게 진행되었다. 또한 생성된 하이드레이트의 해리과정이 진행될 때 역시 서로 다른 해리속도에 의해 조성의 변화를 관찰 할 수 있었다.

• Journal of the Korea Organic Resources Recycling Association
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• 제10권2호
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• pp.132-139
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• 2002

This study was carried out to investigate the effects of aging and soil texture on composting of diesel-contaminated soil. The soils used for this study were silt loam and sand. Target contaminant, diesel oil, was spiked at 10,000mgTPH/kg of dry soil. Aging times of diesel-contaminated soils were 15days and 60days, respectively. Fresh diesel-contaminated soil was also investigated. Moisture content was controlled to 70% of soil field capacity. Mix ratio of soil to sludge was 1:0.3 as wet weight basis. Temperature was maintained at $20^{\circ}C$ Volatilization loss of TPH was below 2% of initial concentration. n-Alkanes lost by volatilization were mainly by the compounds of C10 to C17. Diesel in contaminated soil was mainly removed by biodegradation mechanism. First order degradation rate constant of TPH in sandy soil was ranged from 0.081 to 0.094/day, which is higher than that in silt loam(0.056-0.061/day). From fresh to 60day-aged soils, there was little difference of TPH biodegradation rate between the soils. Carbon recovery ranged from 0.61 to 0.89. TPH degradation rate was highly correlated with $CO_2$ production rate.

• Resources Recycling
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• 제8권4호
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• pp.11-19
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• 1999

Fly ash generated from (he pulverized coal power plant have caused the serious ocean pollution due to the disposal in the ash pond, the life reduction of a power plant and the waste of re-utilizable resource The research to reuse the unburned carbon and mineral composing of the ash has been progressed. In this study. the physical and chemical characteristics of high grade ash and unburned carbon particles obtained from countercurrent column flotation are investigated. The cleaned ash of the less 0,5% loss on Ignition(LOI) in carbon content is a spherical sphere and 39.8${\mu}m$ in size of MMD(Mass Median Diameter). 2.22 $m^2/g$ of specific area. The morphology of high LOI carbon particles is a amorphousness, 76.6 ${\mu}m$ of particle size and 15.2 $m^2/g$ of specific The high grade cleaned ash and the high LOI ash have some difference in the light of physical. chemical and morphological characteristics

• The Korean Journal of Pesticide Science
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• 제9권4호
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• pp.292-302
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• 2005

Condition of Ion-Trap gas chromatography-mass spectrometry (GC-MS) for rapid screening of 206-pesticides residues in agricultural foodstuffs was optimized. As applying a wide-bore column (10 m${\times}$0.53 mm, DF 0.25 um) connected with a fused silica restrictor (0.6 m${\times}$0.1 mm), a significant retention time reduction was obtained. Additionally, the shape of peaks was sharper and higher than classical GC's and GC-MS's, which allowed lower detection limits. To easily manage many spectral data, both of Electron Ionization(EI) and Chemical Ionization(CI) techniques were adopted in screening procedure. At the following steps, MS-MS technique were used to confirm screened analytes in complicated matrices.

• Applied Chemistry for Engineering
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• 제16권3호
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• pp.427-433
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• 2005

The use of the microwave-assisted process for the extraction of effective constituents from ginseng was investigated at various operating conditions. The influence of solvent (ethanol-water, 50% v/v) to ginseng ratio, particle size and applied microwave power on the efficiency of extraction was examined. The microwave extraction system used was custom manufactured so that the intensity of microwave may be varied by using anode-voltage controller. It was found that the ratio of 6 : 1 (vol/mass) gave a good extraction efficiency. Small particle size gave high yield but it caused difficulties in the separation of solvent from the sludge. The higher power was no guarantee of the efficient extraction yield. The more important factor than the employed power was the adequate temperature under sufficient contact time. Using deionized-water as swelling agent, the degree of swelling of ginseng by microwave heating and conventional heating in water-bath was also studied. It was observed that the microwave heating enhanced the swelling much more than the conventional heating. It is believed that this enhanced swelling was responsible for the rapid microwave-assisted extraction rate.

• Journal of the Korean GEO-environmental Society
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• 제19권10호
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• pp.27-34
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• 2018

The effect of cutting-off the leakage was identified by the cement based wall mass constructed in underground, as complete facilities for reinforcement in shear strength of landfill which was subjected to circular failure and for cutting-off the leachate from the costal waste landfill. By (1) visual inspection after underground excavating and (2) compressive strength test for core of underground wall, it could be identified that quality of wall mass constructed in underground was so effective, and by additional test, so as (3) in-situ permeability test in the hole after coring wall mass, (4) analyzing the characteristics of basic components and their profiles through the series of chemical experiments and (5) deciding the general distribution patterns from the chromatograms using GC-MS, it could be identified that watertight and cutting-off the leachate of wall mass constructed in underground was very effective. Therefore, it is concluded that five types of tests suggested in this study can judge the effect of cutting-off the leakage or infiltration of very high concentrated leachate from the waste landfill.

• Journal of Korean Society for Atmospheric Environment
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• 제31권2호
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• pp.143-156
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• 2015

The literature data of the mass concentrations of TSP, $PM_{10}$, and $PM_{2.5}$, and chemical composition of $PM_{2.5}$ (sulfate, nitrate, ammonium, OC, and EC) from 1985 and 2013 at Seoul were collected and the temporal trends were discussed in relation with the policy directions. Generally, the mass concentrations of TSP, $PM_{10}$, and $PM_{2.5}$ at Seoul have showed decreasing trends. However, it is not clear what might be the major reason(s) for the trends. The concentrations of ionic component in $PM_{2.5}$ showed different trends, sulfate being reduced during the 1990s but no trend during the 2000s. The concentrations of nitrate and ammonium were increasing during the 2000s. The concentrations of OC show no apparent trend while that of EC decreased. Further policy directions are suggested based on the temporal trends of the chemical composition in $PM_{2.5}$.

• Korean Journal of Food Science and Technology
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• 제42권6호
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• pp.699-704
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• 2010

Rapeseed oil was stored under different conditions such as in the dark, with UV treatment, and with prooxidantscytochrome C and copper ion. The rapeseed oils stored at different temperatures were analyzed by a mass spectrometrybased electronic nose and discriminant function analysis (DFA). Volatile components in the rapeseed oil increased with storage time, and the discriminant function first score (DF1) moved from a positive position to a negative position as storage time increased. Changes in DF1 were higher under UV treatment than under the dark condition (DF1: $r^2$=0.9481, F=307.03). The different DF1 values (F1) under the dark condition were 0.099, 0.187, and 0.278 as storage temperature increased. The different values under UV treatment were 0.554, 0.588, and 0.542, as storage temperature increased from 4 to $26^{\circ}C$. As concentrations of prooxidants copper ion and cytochrome C increased, amounts of volatile components also increased. These were confirmed by DFA. Furthermore, changes in responses at each ion fragment agreed with reported results for GC/MS, which formed after rancidity of the oil, including pentane, pentanal, 1-pentanol, hexanal, n-octane, 2-hexenal, heptanal, 2-heptenal, decane, 2-octenal, undecane, and dodecane.

• Journal of the Korean earth science society
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• 제28권7호
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• pp.838-846
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• 2007

A measurement system of tri-axial pressure was designed and constructed to measure permeability and resistivity under changing confining pressure. The system was designed to measure the permeability and resistivity of a core simultaneously, consisting of tri-axial supporting device and sets of dual-flow measurement. In this measurement system the permeability and resistivity of a sample can be directly measured and porosity can be obtained using Archie's laws. As for physical properties, artificial core samples are made from mixtures of standard commercial sand and mud of illite. In-situ sediment cores were sampled at the water-depth of 1,800m in the Ulleung Basin East Sea. In order to investigate the effects of confining pressure changes on physical properties, permeability and resistivity changes were monitored with increasing confining pressure. In this study, it was found that with the increase of confining pressure, permeability and porosity tend to decrease and resistivity tend to increase exponentially.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.111.2-111.2
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• 2011

야금학적 방법을 통한 태양전지용 실리콘 제조를 위하여 아크로(Arc furnace)에서 제조된 용융 상태의 금속급 실리콘을 슬래그와 직접 반응시켜 불순물을 제거하는 공정에 관한 연구를 수행하였다. 이를 위해 아크로와 고주파 유도용해로(High-frequency induction furnace)를 이용하여 금속급 실리콘을 제조와 정련 특성 실험을 수행하였다. 본 연구에서 금속급 실리콘을 제조하기 위한 장비로 150kW급-DC 아크로와 300kW급-AC 아크로를 사용하였다. 원재료로 규석, 코크스(Cokes), 숯, 그리고 우드칩(Wood chip)을 실험 비율에 맞춰 아크로 내부에 장입하고, 이를 용융환원 방법을 통해 반응을 시켰다. 이때 생산된 금속급 실리콘의 순도는 약 99.2~99.8% 이었으며, 원재료의 순도, 장입 비율 및 아크로 운전 특성에 따라 편차가 있다. 아크로에서 생산된 금속급 실리콘의 경우 인(phosphorus), 붕소(boron)를 다량 함유하고 있고, 이를 제거하기 위하여 50kW급 고주파 유도용해로 장비를 사용하여 슬래그 정련 실험을 수행하였다. 슬래그 정련시 사용한 성분은 SiO2, CaO 그리고 CaF2 이며, 금속급 실리콘과 슬래그의 질량비 및 반응 시간에 따른 실리콘 불순물 특성을 평가하였다. 실험결과 인과 붕소는 각각 1 ppm 이하, 5 ppm 이하 였으며, 칼슘을 제외한 대부분의 금속 불순물의 경우 0.1~0.2% 임을 확인하였다.