• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1134-1138
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• 2010

호소의 수질오염 문제를 해결하기 위해선 우선 소하천에서 강우유출에 의한 비점오염물질이 어디서 얼마나 발생하는지에 대한 정량적인 조사가 필요하다. 그러나 유역의 오염원에 대한 정량적인 조사가 이루어지려면 많은 비용과 시간 그리고 노력이 필요하다. 따라서 본 연구에서는 대청호 상류유역의 소하천인 안내천을 대상으로 강우유출수 조사를 실시하고, 높은 예측 정확성 때문에 세계적으로 널리 쓰이고 있는 Long-Term Hydrologic Impact Assessment(L-THIA)을 이용하여 실측데이터와 L-THIA 모델의 결과를 비교하였다. 안내천의 유역면적은 16.5 $km^2$로 유역의 약 69.5%가 산림, 농업 및 초지지역이 25.3% 그리고 주거지역이 2.6%로 조사되었다. 수질분석을 위하여 자동수질시료채취기(ISCO sampler 6712)를 설치하여 시간단위의 시료를 채취한 뒤 수질농도를 측정하였다. 수질항목은 유기물질인 $BOD_5$, TOC, T-N, T-P 항목에 대하여 수질오염 공정시험법으로 분석하였다. WHAT 시스템을 이용하여 분리된 직접유출량은 315.5~161,835.1 $m^3$의 범위로 나타났다. 직접유출량을 이용하여 산정한 유역의 EMC 농도는 안내천 유역의 $EMC_{BOD}$는 1.0~2.4 mg/L, $EMC_{TOC}$는 1.429~5.491 mg/L, $EMC_{COD}$는 2.2~10.2 mg/L, $EMC_{TN}$은 2.906~10.864 mg/L, $EMC_{TP}$는 0.029~0.285 mg/L의 범위를 보였다. 또한 실측된 유량과 농도를 이용하여 산정한 오염부하는 안내천 유역이 $BOD_5$ 37.9~390.9 g, $COD_{Mn}$ 0.8~1,657.5 g, TOC 0.54~791.83 g, T-N 0.968~1,758.174 g, T-P 0.011~42.139 g의 범위로 나타났다. L-THIA 모델을 이용하여 직접유출량의 산정된 결과와 실측 결과를 비교 분석한 결과 결정계수와 유효지수가 0.95와 0.93으로 높게 나타나 대청호 상류유역에서 발생하는 유출량을 모의하는데 적절할 것으로 판단된다. 토지이용도와 토양도 그리고 일 강우자료만으로 구축되는 L-THIA 모델을 이용하여 대청호 상류의 소하천 유역에 대하여 비점오염원 유출특성을 해석하는 것이 가능 할 것으로 판단된다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.1
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• pp.8-12
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• 2005

This study was performed to determine the inhibitory effects on cell survival and Quinone reductase induced activity of Aster yomena (AY) on human cancer cells which, using methanol, was extracted and fractionated into five different solvent types: hexane (AYMH), ethylether (AYMEE), ethylacetate (AYMEA), butanol (AYMB) and aqueous (AYMA) partition layers. The experiment was conducted to determine cytotoxicity of various Aster yomena partition layers on HepG2, HeLa and MCF-7 cells by MTT assay. Among various partition layers of Aster yomena, A YMEE and A YMEA showed the strong cytotoxic effects on all cancer cell lines we used. The Quinone reductase (QR) induced activity on HepG2 cells, A YMH at a does of 100 $\mu$g/mL was 2.46 times more effective compared to the control value of 1.0.

• Membrane Journal
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• v.28 no.1
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• pp.62-66
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• 2018

In this study the cleaning spherical beads with same density as water were fabricated. Bead moving velocity was measured with respect to the aeration rate and bead concentration in water reservoir. The permeation experiments for FR (filtration and relaxation) and SFCO (sinusoidal filtration continuous operation) modes were simultaneously carried out under the condition of 1 to 3% cleaning spherical bead concentration, 20 LMH and 500 mL/min aeration rate in the MLSS 8,000 mg/L activated sludge solution. The used membrane was the $90cm^2$ effective area and $0.4{\mu}m$ nominal pore size flat membrane. The TMP (transmembrane pressure) decreased as the bead concentration increased, and was shown most effective in FR mode with 2% bead concentration.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.505-510
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• 2015

This study investigated formation potential of 16 disinfection byproducts (DBPs) (e.g., g trihalomethanes, haloacetic acids, haloacetonitriles, chloral hydrate, etc.) upon chlorination of raw water at various pH, water temperatures, and chlorine doses. We also compared the DBP formation potential (DBPFP) of raw and filtered waters. Most of DBPs were formed higher at neutral pH, but dichloroacetic acid, chloroform, and bromodichloromethane were formed higher over pH 7. As water temperature increased, concentrations of chloral hydrate, haloacetic acids, and haloacetonitriles linearly increased while that of trihalomethanes exponentially increased. Formation of chloral hydrate, trihalomethanes, and trihaloacetonitriles significantly increased up to 2.0 mg/L $Cl_2$ of chlorine addition, then gradually increased at 2.0~5.6 mg/L $Cl_2$. Filtered water formed less DBPs than raw water in most DBPs except for trihalomethanes.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.17-21
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• 2001

We analyzed the luminance in the visual light region and the size of pupil by the luminance to estimate an UV-A line cut efficiency in the lens. The size of pupil by the luminance(L) was given by ${\Phi}=d-e{\cdot}tanh(f{\cdot}logL)$ and the transmittance efficiency value of a size of pupil was given by $T_r(r)=1-gr^2+hr^4$. We derived the absolute cut efficiency value ${\alpha}$ and the exclusion index $b=(1-{\alpha}){\times}100%$ about the UV-A in the $320{\sim}400nm$ regions. The ${\alpha}$ and b values were obtained respectively 0.018, 0.31, 0.273, 0.153 and 98, 69, 72, 85% of Uv-cut Lens, CR-39, red color and blue color.

• Journal of Chest Surgery
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• v.35 no.9
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• pp.672-674
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• 2002

A 40-years-old male with dilated cardiomyopathy(DCMP) and end-stage heart failure had undergone partial left ventriculectomy(PLV) in July 1997 and then underwent cardiac transplantation in January 1999. Three months later he showed increased ejection fraction (EF) from 26% to 42.6%, decreased left ventricular end diastolic diameter(LVEDD) from 71mm to 45mm, cardiac output(CO) 3.95 L/min and cardiac index(CI) 2.28 L/min/m$^2$echocardiographically. Eight months later, left ventriclular end diastolic and systolic diameters increased to 56 and 51 mm respectively and EF decreased to 17% in echocardiographic follow-up. He had been on maximum medication until he underwent cardiac transplantation 18 months after the PLV. Consecutive myocardial biopsies (1, 3 and 6 month later) showed ISHLT (international society of heart and lung transplantation) class la and the treatment for rejection was not needed until now on. We report a partial left ventriculectomy as a successful bridge to cardiac transplantation in a patient with DCMP and end-stage heart failure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.2
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• pp.85-91
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• 2016

The Positive Temperature Coefficient (PTC) is used for cabin air heating of a battery electric vehicle, which is different from conventional vehicles. Since the PTC heater consumes a large quantity of power in a parasitic manner, many valuable studies have been reported in the field of alternative heat pumps. In this study, a model for an R134a heat pump taking into account the thermal environment of the cabin was developed for a MATLAB/SIMULINK(R) platform. Component and cabin models are validated with reference values. Results show that the heat pump is more competitive for parasitic power consumption over all ambient temperature conditions. Additionally, the method of waste heat recovery to overcome disadvantages when temperatures are below zero is applied to efficiently operate the heat pump.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.77-84
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• 2000

In this paper, we modelized the multipath fading to Nakagami-m distribution fading channel which can be applied to the extended mobile communication channel environment. We assumed that the phase difference with reference signal happened in the received signal and in the receiver PLL(Phase Locked Loop) is the phase error. To correct the error we propose new RAKE receiver using PLL. In addition, we analyze the performance of DS/SS(Direct Sequence/spread Spectrum) system according to the gain of PLL,$\gamma_n$, the number of RAKE receiver branch L and MIP(Multipath Intensity Profile)'s exponential decay $\delta$. As a result, when the proposed RAKE receiver L Is increased and the $\delta$ is decreased the performance of the system gets better. Futhermore when PLL gain was 30dB, phase is identified. That is when the PLL gain is 30dB, the performance equals with the perfect coherent system's. Therefore, we can correct the phase error by using the proposed RAKE receiver and we proved that the PLL's requested limit gain should be 30dB.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.457-465
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• 2010

In this study, a Taylor series (T-S) model based on the Arrhenius, McVetty, and Monkman-Grant equations was developed using a mathematical analysis. In order to reduce fitting errors, the McVetty equation was transformed by considering the first three terms of the Taylor series equation. The model parameters were accurately determined by a statistical technique of maximum likelihood estimation, and this model was applied to the creep data of alloy 617. The T-S model results showed better agreement with the experimental data than other models such as the Eno, exponential, and L-M models. In particular, the T-S model was converted into an isothermal Taylor series (IT-S) model that can predict the creep strength at a given temperature. It was identified that the estimations obtained using the converted ITS model was better than that obtained using the T-S model for predicting the long-term creep life of alloy 617.

• Journal of the Korean Chemical Society
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• v.45 no.5
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• pp.422-428
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• 2001

Retention relative times(RRTs) of PAH molecules and their derivatives in gas chromatography are trained and predicted in testing sets using a multiple linear regression(MLR) and an artificial neural network(ANN). The main descriptors of PAHs and their derivatives in QSRR are the square root of molecular weight(sqmw), molecular connectivity($^1{\chi}_v$), molecular dipole moment(D) and length-to-breadth ratios(L/B). The results of MLR shows that a heavy molecule has a propensity for long retention time. L/B closely related with slot model is a good descriptor in MLR. On the other hand, ANN which is not effected by the linear dependencies among the descriptors were exclusively based on molecular weight and molecular dipole moment. The variances which shows the accuracy of prediction for retention times in testing sets are 1.860, 0.206 for MLR and ANN, respectively. It was shown that ANN can exceed the MLR in prediction accuracy.