• Title, Summary, Keyword: gas hydrate

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Changes in the Concentrations of the Tap Water Chlorination By-Products by Heating during Cooking, and Human Ingestion Exposure (조리시 가열에 따른 수돗물 중 염소소독부산물의 농도 변화와 인체 섭취 노출)

  • 김희갑;이수형
    • Environmental Analysis Health and Toxicology
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    • v.14 no.1_2
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    • pp.35-43
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    • 1999
  • A number of disinfection by-products (DBPs) are formed as a result of the addition of chlorine into the public water supply and some of them have been suggested to cause adverse health effects on humans. However, the estimation of human ingestion exposure to each DBP has been performed simply by multiplying the concentration of a chemical in the cold tap water by the volume of water consumed during a given period of time. However, a questionnaire concerning water consumptions administered to sixty people residing in Chunchon showed that the volume of tap water consumed accounted for approximately 70% of the total volume of water consumed and that of heated water represented approximately 94% of tap water ingested. Heating durations for water-containing foods (e. g., soups and pot stews) and heated beverages (e. g., barley tea) were grouped into 10, 20, 30, and 35 minutes. Based on these time frames, an aluminum pot containing one liter of tap water was heated for the above respective time periods using a gas range to determine the variations of the concentrations of individual DBPs by heating. The pH and total residual chlorine were measured before and after heating. Collected water samples were carried to the laboratory and analyzed for eight DBPs and total organic carbon. Chloroform, bromodichloromethane, chloral hydrate, 1, 2-dichloro-2-propanone, 1, 1, 1-trichloropropanone, and dichloroacetonitrile were not detected following heating for 10 minutes and longer. The concentration of dichloroacetic acid (DCAA) was elevated with heating duration, resulting in the averages of 2.0, 3.1, 4.7, and 12 times the initial concentration, respectively, for 10, 20, 30, and 35 minute heating periods. On the other hand, the concentration of trichloroacetic acid (TCAA) decreased with heating duration, with 0.65, 0.40, 0.34, and 0.19 times lower than the initial concentration. Therefore, it is suggested that ingestion exposure to DCAA increases with heating duration but that ingestion exposure to TCAA decreases. In addition, while the amount of DCAA was elevated at the initial time periods (10 or 20 minutes) and then slowly decreased, that of TCAA was rapidly decreased. In conclusion, water-heating processes during cooking influence the concentrations of individual DBPs in the tap water, with lower levels for volatile DBPs and TCAA, and higher levels for DCAA. Therefore, concentration change needs to be taken into consideration in the estimation of human ingestion exposure to DBPs.

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Comparative analysis on range of application of technology convergence as a means of technological innovation (기술혁신 수단으로써 기술융합 이론의 적용 범위에 대한 비교 연구)

  • Choi, Hyukjoon;Lee, Youah
    • 한국신재생에너지학회:학술대회논문집
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    • pp.142-142
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    • 2010
  • 일반적으로 기술융합이라는 용어는 IT, BT, NT 등 성격이 다른 큰 범주에서 기술간의 결합으로 인식되고 있다. 현재까지의 기술융합 연구들은 IT기술을 중심으로 한 융합과 관련 국가 정책에 관한 것이 대부분을 차지하고 있어 큰 기술 범주 위주에 국한되어 있다. 하지만 동일한 목적을 위해 수행하는 유사 기술영영에서의 기술융합 역시 기술혁신의 수단으로 간과할 수 없는 영역이다. 실제로 미국, 유럽 등의 선진국에서는 기술융합 전담기관을 신설하여 프로젝트 내의 기술간 융합에 관심을 갖고 있지만, 국내에서는 프로젝트 범위의 기술융합 가능성 및 실효성에 대한 연구가 부족한 실정이다. 이에 본 연구에서는 지식경제부에서 수행하는 가스하이드레이트 연구개발사업을 실증사례로 하여 프로젝트 범위의 기술 융합에 관하여 기술융합의 필요성, 적용가능성, 실효성에 초점을 맞추어 고찰하였다. 가스하이드레이트 개발 사업은 지식경제부 내 가스하이드레이트 개발사업단 주관으로 2005년에 시작되었으며 2014년까지 I 지역 탐사 및 시추, II 지역 탐사 및 시추, 시험생산의 3단계의 달성목표를 가지고 있다. 가스하이드레이트는 천연가스가 저온 고압 상태에서 물과 결합해 형성된 고체 에너지로 화석연료 고갈에 따라 이를 대체할 가장 유력한 청정에너지원으로 주목받고 있다. 현재 가스하이드레이트 개발사업단에서는 지구물리탐사분야 지질지화학분야 개발생산분야로 세부 기술모듈을 형성하여 목표달성을 위해 노력하고 있지만, 중과제간 교류가 부족한 상황으로 인해 목표달성을 위한 기술력의 확보 및 향후 상업생산에 대한 불확실성이 증가하고 있는 상황이다. 이와 같은 상황을 해결하기 위해서 기술개발 및 혁신의 수단인 기술융합의 필요성이 증가하고 있다. 기술혁신은 기초연구, 응용연구, 개발, 학습, 투자 등의 일련의 과정을 거쳐 경제적 성과와 사회적 영향을 만들어내는 개념으로 정의 할 수 있다. 기술혁신을 이루어내는 가장 중심적인 역할을 담당하는 기술융합은 2개 이상의 요소기술들이 결합하여 기술이 갖지 않는 새로운 기능을 발휘하는 기술혁신의 한 현상으로 정의할 수 있다. 기술융합은 21세기 초에 접어들어 급속하게 변화하는 양상을 보이며 예상보다 경제에 더 큰 영향을 미치고 있다. 가스하이드레이트 각 단계에서의 애로점을 극복하기 위한 기술혁신을 위해 지구물리탐사 지질지화학 개발생산분야간의 융합의 가능성 등을 타진해본 결과, 각 기술융합들을 기술융합 유형에 맞춰 분류할 수 있었으며 유형별 적용가능성과 기대효과 측면에서 비교분석을 수행하였다. 분석의 정밀도를 높이기 위하여 기술융합 유형에 대한 이론과 실제 가스하이드레이트 전문가들과의 설문을 통해 비교분석을 실시하였다. 가스하이드레이트 실증 사례에 대한 분석 결과, 기술융합 이론은 기존의 큰 기술범주뿐만 아니라 작은 범주에도 적용할 수 있으며, 필요성과 적용가능성, 실효성 면에서도 충분한 고찰을 통해 기술융합 이론의 적용 범위를 좁히면 더 많은 연구와 융합기술을 얻을 수 있다는 결론을 얻을 수 있다.

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Hydration Reaction of Non-Sintering Cement Using Inorganic Industrial Waste as Activator (무기계 산업폐기물을 자극제로 이용한 비소성 시멘트의 수화반응)

  • Mun, Kyoung-Ju;Lee, Chol-Woong;So, Seung-Young;Soh, Yang-Seob
    • Journal of the Korea Concrete Institute
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    • v.18 no.2
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    • pp.267-274
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    • 2006
  • Greenhouse gas reduction will be highlighted as the most pending question in the cement industry in future because the production of Portland cement not only consumes limestone, clay, coal, and electricity, but also release waste gases such as $CO_2,\;SO_3$, and NOX, which can contribute to the greenhouse effect and acid rain. To meet the increase of cement demand and simultaneously comply with the Kyoto Protocol, cement that gives less $CO_2$ discharge should be urgently developed. This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also Investigates the hydration reaction of NSC through analysis of scanning electron microscopy(SEM), X-ray diffraction(XRD), differential thermal analysis(DTA), and pH. Results obtained from analysis of the hydrate have shown that the glassy films of GBFS are destroyed by the activation of alkali and sulfate, ions eluted from the inside of GBFS react with PG and produce ettringite, and consequently the remaining component in GBFS slowly produced C-5-H(I) gel. Here, PG is considered not only to play the role of simple activator, but also to work as a binder reacting with GBFS.

Geotechnical Engineering Characteristics of Ulleung Basin Sediment, East Sea (동해, 울릉 분지 심해토의 지반공학특성)

  • Lee, Chang-Ho;Yun, Tae-Sup;J.C., Santamarina;Bahk, Jang-Jun;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.25 no.6
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    • pp.17-29
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    • 2009
  • There has been an increase in the investigation of deep sea sediments with a consequent increase in the amount of energy required to undertake these investigations. The geotechnical characteristics of Ulleung Basin sediment are explored by using depressurized specimens following methane production tests carried out on pressured core samples obtained at 2,100 m water depth and 110 m below sea floor. Geotechnical index tests, X-ray diffraction, and scanning electron microscope are conducted to identify the geotechnical index parameters, clay mineralogy, chemical composition, and microstructure of the sediments. Compressibility, and elastic and electromagnetic wave parameters are investigated for two samples by using a multi sensing instrumented oedometer cell. The strength chatracteristics are obtained by the direct shear tests. The dominant clay minerals are mostly kaolinite, illite, chlorite, and calcite. The SEM shows a well-developed flocculated structure of the microfossil. Void ratio, electrical resistivity, real permittivity, conductivity, and shear wave velocity show bi-linear behavior with the effective vertical stress: as the vertical effective stress increases. The friction angle obtained by the direct shear test is about $21^{\circ}$, which is similar to the value observed in the Ulleung Basin sediments. This study shows that the understanding of the behavior acting on the diatomaceous marine sediment is important because it often maintains the useful energy resources such as gas hydrate and so will be the new engineering field in the next generation.

Numerical studies of information about elastic parameter sets in non-linear elastic wavefield inversion schemes (비선형 탄성파 파동장 역산 방법에서 탄성파 변수 세트에 관한 정보의 수치적 연구)

  • Sakai, Akio
    • Geophysics and Geophysical Exploration
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    • v.10 no.1
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    • pp.1-18
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    • 2007
  • Non-linear elastic wavefield inversion is a powerful method for estimating elastic parameters for physical constraints that determine subsurface rock and properties. Here, I introduce six elastic-wave velocity models by reconstructing elastic-wave velocity variations from real data and a 2D elastic-wave velocity model. Reflection seismic data information is often decoupled into short and long wavelength components. The local search method has difficulty in estimating the longer wavelength velocity if the starting model is far from the true model, and source frequencies are then changed from lower to higher bands (as in the 'frequency-cascade scheme') to estimate model elastic parameters. Elastic parameters are inverted at each inversion step ('simultaneous mode') with a starting model of linear P- and S-wave velocity trends with depth. Elastic parameters are also derived by inversion in three other modes - using a P- and S-wave velocity basis $('V_P\;V_S\;mode')$; P-impedance and Poisson's ratio basis $('I_P\;Poisson\;mode')$; and P- and S-impedance $('I_P\;I_S\;mode')$. Density values are updated at each elastic inversion step under three assumptions in each mode. By evaluating the accuracy of the inversion for each parameter set for elastic models, it can be concluded that there is no specific difference between the inversion results for the $V_P\;V_S$ mode and the $I_P$ Poisson mode. The same conclusion is expected for the $I_P\;I_S$ mode, too. This gives us a sound basis for full wavelength elastic wavefield inversion.

Trace Interpolation using Model-constrained Minimum Weighted Norm Interpolation (모델 제약조건이 적용된 MWNI (Minimum Weighted Norm Interpolation)를 이용한 트레이스 내삽)

  • Choi, Jihyun;Song, Youngseok;Choi, Jihun;Byun, Joongmoo;Seol, Soon Jee;Kim, Kiyoung;Lee, Jeongmo
    • Geophysics and Geophysical Exploration
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    • v.20 no.2
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    • pp.78-87
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    • 2017
  • For efficient data processing, trace interpolation and regularization techniques should be antecedently applied to the seismic data which were irregularly sampled with missing traces. Among many interpolation techniques, MWNI (Minimum Weighted Norm Interpolation) technique is one of the most versatile techniques and widely used to regularize seismic data because of easy extension to the high-order module and low computational cost. However, since it is difficult to interpolate spatially aliased data using this technique, model-constrained MWNI was suggested to compensate for this problem. In this paper, conventional MWNI and model-constrained MWNI modules have been developed in order to analyze their performance using synthetic data and validate the applicability to the field data. The result by using model-constrained MWNI was better in spatially aliased data. In order to verify the applicability to the field data, interpolation and regularization were performed for two field data sets, respectively. Firstly, the seismic data acquired in Ulleung Basin gas hydrate field was interpolated. Even though the data has very chaotic feature and complex structure due to the chimney, the developed module showed fairly good interpolation result. Secondly, very irregularly sampled and widely missing seismic data was regularized and the connectivity of events was quite improved. According to these experiments, we can confirm that the developed module can successfully interpolate and regularize the irregularly sampled field data.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2011 (설비공학 분야의 최근 연구 동향: 2011년 학회지 논문에 대한 종합적 고찰)

  • Han, Hwa-Taik;Lee, Dae-Young;Kim, Seo-Young;Choi, Jong-Min;Paik, Yong-Kyoo;Kim, Su-Min
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.6
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    • pp.521-537
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    • 2012
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2011. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) Research trends of thermal and fluid engineering have been surveyed as groups of fluid machinery and fluid flow, thermodynamic cycle, and new and renewable energy. Various topics were presented in the field of fluid machinery and fluid flow. Research issues mainly focused on the rankine cycle in the field of thermodynamic cycle. In the new and renewable energy area, researches were presented on geothermal energy, fuel cell, biogas, reformer, solar water heating system, and metane hydration. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer, nanofluids and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer above liquid helium surface in a cryostat, methane hydrate formation, heat and mass transfer in a liquid desiccant dehumidifier, thermoelectric air-cooling system, heat transfer in multiple slot impinging jet, and heat transfer enhancement by protrusion-in-dimples. In the area of pool boiling and condensing heat transfer, researches on pool boiling of water in low-fin and turbo-B surfaces, pool boiling of R245a, convective boiling two-phase flow in trapezoidal microchannels, condensing of FC-72 on pin-finned surfaces, and natural circulation vertical evaporator were actively performed. In the area of nanofluids, thermal characteristics of heat pipes using water-based MWCNT nanofluids and the thermal conductivity and viscosity were measured. In the area of industrial heat exchangers, researches on fin-tube heat exchangers for waste gas heat recovery and Chevron type plate heat exchanger were implemented. (3) Refrigeration systems with alternative refrigerants such as $CO_2$, hydrocarbons, and mixed refrigerants were studied. Heating performance improvement of heat pump systems were tried applying supplementary components such as a refrigerant heater or a solar collector. The effects of frost growth were studied on the operation characteristic of refrigeration systems and the energy performance of various defrost methods were evaluated. The current situation of the domestic cold storage facilities was analyzed and the future demand was predicted. (4) In building mechanical system fields, a variety of studies were conducted to achieve effective consumption of heat and maximize efficiency of heat in buildings. Various researches were performed to maximize performance of mechanical devices and optimize the operation of HVAC systems. (5) In the fields of architectural environment and energy, diverse purposes of studies were conducted such as indoor environment, building energy, and renewable energy. In particular, renewable energy and building energy-related researches have mainly been studied as reflecting the global interests. In addition, various researches have been performed for reducing cooling load in a building using spot exhaust air, natural ventilation and energy efficiency systems.