• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.246-249
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• 2007

상변화 물질을 취급하는 수치해석에서는 온도, 압력, 체적, 엔탈피, 엔트로피 등의 열역학적 성질들의 수치값이 필요하다. 그러나 열역학적 성질들은 증기표나 선도 등의 형태로 주어지기 때문에 그대로 이용할 수는 없고 모델링하여 사용하여야 한다. 본 연구에서는 2차 스플라인 보간법과 비교함으로써, 과열증기의 모델링에 신경회로망의 적용 가능성을 검토하였다. 신경회로망은 온도와 압력, 2개의 입력에 대하여 비체적, 엔탈피 및 엔트로피, 3개의 출력을 얻을 수 있도록 입력층, 은닉층 및 출력층으로 구성되었다. 스플라인 보간법은 2차 다항식을 사용하였으며, 주어진 압력에 대한 소구간의 온도에 적용하였다. 신경회로망 모델링은 많은 출력 범위에서 2차 스플라인 보간법보다 우수한 백분율 오차를 보였으며, 이 결과로부터 과열증기 모델링에 신경회로망이 아주 강력한 방법임을 확인하였다.

• Ocean and Polar Research
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• 제25권3호
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• pp.237-247
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• 2003

The temporal dynamics of the meiofauna community in Marian Cove, King George Island were observed from January 22 to October 29 1996. Generally, 14 taxa of metazoan meiofauna were found. Nematodes were dominant comprising 90.12% of the community, harpacticoid 6.55%, and Kinorhynchs 1.54%. Meiofauna abundance increased monthly from January to May 1996, while varying in abundance after August 1996. Overall mean abundance of metazoan meiofauna was $2634ind./10cm^2$ during the study periods, which is about as high as that found in temperate regions. Nematodes were most abundant representing $2399ind./10cm^2$. Mean abundance of harpacticoids, including copepodite and nauplius was $131ind./10cm^2$ by kinorhynchs $(26ind./10cm^2)$. The overall abundance of other identified organisms was $31ind./10cm^2$ Other organisms consisted of a total of 11 taxa including Ostracoda $(6ind./10cm^2)$, Polycheata $(7ind./10cm^2)$, Oligochaeta $(8ind./10cm^2)$, and Bivalvia $(6ind./10cm^2)$. Additionally, protozoan Foraminifera occurred at the study area with a mean abundance of $263ind./10cm^2$. Foraminiferans were second in dominance to nematodes. The dominant taxa such as nematodes, harpacticoids, kinorhynchs and the other tua were trained and extensively scattered in the map through the Kohonen network. The temporal pattern of the community composition was most affected by the abundance dynamics of kinorhynchs and harpacticoids. The neural network model also allowed for simulation of data that was missing during two months of inclement weather. The lowest meiofauna abundance was found in August 1996 during winter. The seasonal changes were likely caused by temperature and salinity changes as a result of meltwater runoff, and the physical impact by passing icebergs.

• Journal of the Korean Wood Science and Technology
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• 제44권4호
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• pp.477-493
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• 2016

A single process using hot water (0% green liquor) and green liquor (GL) was investigated for pre-pulping extraction on two types of raw material. The GL was applied at different alkali charges of 0-5% on a dry wood weight basis. The extractions were performed at an H-factor 900 at $180^{\circ}C$. The 0% and 3% GL extraction detected acetic acid (AA) at 10.02 and $9.94g/{\ell}$, extracts derived from hardwood, 2.46 and $3.76g/{\ell}$, extracts derived from softwood, respectively. The single liquid-liquid extraction (LLE) was studied using tri-n-alkylphosphine oxide (TAPO). Response surface methodology (RSM) was employed as an efficient approach for predictive model building and optimization of AA recovery conditions. The extraction of AA was evaluated with a three-level factorial design. Three independent variables, pH (0.5-3.5), temperature ($25-65^{\circ}C$), and residence time (24-48 min) were investigated. Applying the RSM models obtained, the optimal conditions selected of extracts derived from hard- and softwood with a 3% GL were approximately pH 1.4, $26.6^{\circ}C$, 43.8 min and approximately pH 0.7, $25.2^{\circ}C$, 24.6 min, respectively. The predicted and experimental values of AA recovery yield were similar whilst sugar retention was 100%.

• 한국염색가공학회지
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• 제8권1호
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• pp.83-89
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• 1996

Carbon black has been used as a particulate soil to prepare artificial soiled fabrics for detergent study but it has two major defects. The one is the difficulty of quantitative analysis of carbon black for evaluate the detergency, the other is that there is no reliable correlation between the removal of carbon black and oily soil which is the major component of natural soil. In this study ferric oxinate was used as a particulate soil since it is in black color and can be soiled on fabric by suspension in water or by solution in chloroform and it is easily analysed quantitatively by extracting it from soiled fabric with chloroform to get correct value of soil removal. The characteristics of soil removal of ferric oxinate were compared with that of carbon black and Sudan black, an oil soluble dye, which had been proved that it's detergency correlated with that of oily soil The soil removal of ferric oxinate and Sudan black estimated from quantitative analysis and from K/S value were in good agreement whereas the result calculated by simple reflectance was consistently low. The soil removal of ferric oxinate was exceeded from that of carbon black without regard to surfactants, Triton and Las, but the effect of washing conditions such as temperature and washing time on soil removal of both soils with different suffactants showed no considerable difference. Though the soil removal of Sudan black was little effected by the conditions, the soil removal in Triton exceeded considerably that of in Las, which is the characteristic of oily soil. Thus the soil removal of Sudan black was in good agreement with ferric oxinate in Triton, a non-ionic surfactant, and with carbon black in Las, an artionic surfactant. We concluded that ferric oxinate is a more realistic model particulate soil for artificial soiled cotton fabric washed with non-ionic surfactant than carbon black.

• 한국환경농학회지
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• 제31권2호
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• pp.113-121
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• 2012

BACKGROUND: The Doam watershed in Korea has been managed for the reduction and the prevention of non-point source pollution since 2007. Especially, the water quality of the Doam reservoir is a primary issue related to the Doam dam reoperation. We have carried out the modeling to evaluate the water quality based on suspended solids (SS) of the Doam watershed and the Doam reservoir. Two powerful hydrological and water quality models (HSPF and CE-QUAL-W2) were employed to simulate the combined processes of water quantity and quality both in the upland watershed of the Doam reservoir and the downstream waterbody. METHODS AND RESULTS: The HSPF model was calibrated and validated for streamflow and SS. The CE-QUAL-W2 was calibrated for water level, water temperature, and SS and was validated for the only water level owing to data lack. With the parameters obtained through the appropriate calibration, SS concentrations of inflow into and in the Doam reservoir were simulated for three years (2008, 2004 and 1998) of the minimum, the average, and the maximum of total annual precipitation during recent 30 years. The annual average SS concentrations of the inflow for 2008, 2004, and 1998 were 8.6, 10.9, and 18.4 mg/L, respectively and those in the Doam reservoir were 9.2, 13.8, and 21.5 mg/L. CONCLOUSION(s): The results showed that more intense and frequent precipitation would cause higher SS concentration and longer SS's retention in the reservoir. The HSPF and the CE-QUAL-W2 models could represent reasonably the SS from the Doam watershed and in the Doam reservoir.

• 한국작물학회지
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• 제53권1호
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• pp.8-14
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• 2008

Ammonia ($NH_3$) volatilization from a silty clay loam paddy soil applied with non, straight urea, and coated urea, respectively, under transplanting in Milyang, Korea from 2002 and 2003 was simulated by a Water and Nitrogen Management Model (WNMM). Based on the data from the in-situ measurements, $NH_3$ volatilization during the rice growth was 6.04% and 1.46% of the applied nitrogen (N) from straight urea and coated urea, respectively. The bulk aerodynamic approach in WNMM satisfactorily predicted the difference in $NH_3$ loss during the given rice growing seasons from the two urea fertilizers. $R^2$ for the correlation between the predicted and observed NH3 loss during the calibration year (2002) was 0.53 less than 0.68 of the application year (2003). This difference could be due to the weather condition such as heavy rainfall and temperature during the calibration year.

• 한국초전도ㆍ저온공학회논문지
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• 제17권1호
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• pp.32-35
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• 2015

Many kinds of high temperature superconducting (HTS) devices are being developed due to its several advantages. In particular, the advantages of HTS devices are maximized under the DC condition. A line commutated converter (LCC) type high voltage direct current (HVDC) transmission system requires large capacity of DC reactors to protect the converters from faults. However, conventional DC reactor made of copper causes a lot of electrical losses. Thus, it is being attempted to apply the HTS DC reactor to an HVDC transmission system. The authors have developed a 8 mH class HTS DC reactor and a model-sized LCC type HVDC system. The HTS DC reactor was operated to analyze its operational characteristics in connection with the HVDC system. The voltage at both ends of the HTS DC reactor was measured to investigate the stability of the reactor. The voltages and currents at the AC and DC side of the system were measured to confirm the influence of the HTS DC reactor on the system. Two 5 mH copper DC reactors were connected to the HVDC system and investigated to compare the operational characteristics. In this paper, the operational characteristics of the HVDC system with the HTS DC reactor according to firing angle are described. The voltage and current characteristics of the system according to the types of DC reactors and harmonic characteristics are analyzed. Through the results, the applicability of an HTS DC reactor in an HVDC system is confirmed.

• 대한원격탐사학회지
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• 제36권4호
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• pp.587-607
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• 2020

Soil moisture is essential information for meteorological and hydrological analyses. To date, many efforts have been made to achieve the two goals for soil moisture data, i.e., the improvement of accuracy and resolution, which is very challenging. We presented an ensemble downscaling method for quality improvement of gridded soil moisture data in terms of the accuracy and the spatial resolution by the integration of BMA (Bayesian model averaging) and ATPRK (area-to-point regression kriging). In the experiments, the BMA ensemble showed a 22% better accuracy than the data sets from ESA CCI (European Space Agency-Climate Change Initiative), ERA5 (ECMWF Reanalysis 5), and GLDAS (Global Land Data Assimilation System) in terms of RMSE (root mean square error). Also, the ATPRK downscaling could enhance the spatial resolution from 0.25° to 0.05° while preserving the improved accuracy and the spatial pattern of the BMA ensemble, without under- or over-estimation. The quality-improved data sets can contribute to a variety of local and regional applications related to soil moisture, such as agriculture, forest, hydrology, and meteorology. Because the ensemble downscaling method can be applied to the other land surface variables such as temperature, humidity, precipitation, and evapotranspiration, it can be a viable option to complement the accuracy and the spatial resolution of satellite images and numerical models.

• 동력기계공학회지
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• 제22권1호
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• pp.48-55
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• 2018

It has recently been reported that methanol fuel has been used in the product carrier with established duel fuel engine, which has been greatly reducing emissions of $CO_2$, NOx and SOx from the engine. However, to use methanol alone as fuel oil in a general diesel engine, design modification of cylinder head is needed because the ignition aid device or the duel fuel injection system is needed. On the other hand, only if the mixer is installed on the fuel oil supply line, diesel oil - methanol blending oil can be used as fuel oil for the diesel engine, but there is a problem of the phase separation when two fuels are mixed. In this study, diesel oil and methanol were blended compulsorily in preventing the phase separation with installing agitators and a fuel oil boost pump on fuel line of a test engine. Also, cylinder pressure and fuel consumption quantity were measured according to engine load and methanol blending ratio, and indicated mean effective pressure, heat release rate and combustion temperature obtained from the single zone combustion model were analyzed to investigate the effects of latent heat of vaporization of methanol on combustion stability and characteristics. As a result, the combustion stability and characteristics of 10% methanol blending oil are closest to the those of diesel oil, and it could be used as fuel oil in existing diesel engines without deterioration of engine performance and combustion characteristics.

• 콘크리트학회논문집
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• 제28권6호
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• pp.665-672
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• 2016

본 연구는 상전이물질이 시멘트 모르타르의 수화특성 및 강도특성에 미치는 영향을 평가하기 위하여 실시되었다. 이를 위하여 바륨 및 스트론튬계 상전이물질을 사용하였으며, 상전이물질 혼입률 1~5%에 대한 실험을 수행하였으며, 시멘트 모르타르 작업성 평가, 간이단열온도상승 실험, 압축 및 휨 강도 평가를 실시하였다. 실험결과 상전이물질의 혼입은 시멘트 모르타르의 수화열 감소에 효과적인 것으로 나타났으며, 바륨 기반 PCM을 사용할 경우 흐름성능이 다소 감소하는 것으로 나타났다. 압축 휨 강도의 경우 상전이물질의 혼입률이 증가함에 따라 감소하는 경향을 나타내었으며, PCM을 사용할 경우 혼입률에 따라 압축강도 발현추이의 변화가 발생하였다. 따라서 본 연구에서는 상전이물질이 혼입률에 따른 압축강도 추정식을 제시하였다.