• 한국응용과학기술학회지
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• 제25권4호
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• pp.459-468
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• 2008

Methyl methacrylate(MMA) was grafted onto microcrystalline cellulose(MCC) with ceric ammonium nitrate(CAN) as a redox initiator at the various conditions. The cellulose triacetate(CTA) composite films added MCC and MMA-grafted MCC powders were prepared on a glass plate. The graft yield(GY) and graft efficiency(GE) of the grafted MCC were calculated with the simple equations by the weight balance method. The double bond of C=O on the grafted MCC surfaces was confirmed by the fourier transform infrared spectroscopy with attenuated total reflection(FT-IT ATR) spectrophotometer. After grafting, the degree of crystallinity of cellulose powders was decresed by judging from x-ray diffraction(XRD) data. Scanning electron microscope(SEM) photos showed the only solvent and CAN solution could change the roughness of MCC powders and the effect of powder dispersions in composite matrix. The tensile strength of MCC/CTA composite films was decreased with increase of MCC powder contents. When 5% grafted MCC was added, the tensile strength of grafted MCC/CTA composite films was increased from 82.3 MPa to 97.2 MPa. The thermal property of powders was also analyzed by the thermogravimetric analysis(TGA).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.74-74
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• 2010

The aqua-plasma is the non-thermal plasma in electrical conductive electrolyte by generates the vapor film layer on the immersed metal electrode surface. This plasma can generate the hydroxyl radical by dissociate the water molecule with the plasma electron. To develop the plasma discharge device for high efficiency in the hydroxyl radical generation, proper model for estimation of plasma power is necessary. In this work, the 1-D spherical model was developed, considering temperature dependence material constants. The relation between the plasma power and hydroxyl generation was also studied by the comparison between the optical emission intensity from the hydroxyl radical using monochromator and estimated plasma power. First, the thickness of vapor layer thickness was estimated using the Navier-Stokes fluid equation in order to calculate the discharge E-field inside vapor layer. Using the E-field magnitude and power balance on the plasma generation, it was possible to estimate the plasma power. The plasma power was assumed to uniformly fill the vapor layer and the temperature of vapor layer was fixed in the boiling temperature of electrolyte, 375K. In the experiment, the aqua-plasma was discharged in the saline by applied the voltage on the bipolar electrode. The range of applied voltage was 234 to 280V-rms in the frequency of 380 kHz. Two type electrodes were produced with two ${\Phi}0.2$ tungsten. The plasma power was estimated from the V-I signal from the two high voltage probes and current probe. The estimated plasma power agreed with the profile of emission intensity when the plasma discharged between the metal electrode and vapor layer surface. However, when the plasma discharged between the metal electrodes, the increasing rate of emission intensity was lower than the increase of plasma power. It implies that the surface reaction is more sufficient rather than the volume reaction in the radical generation, due to the high density of water molecule in the liquid.

• 폴리머
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• 제29권4호
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• pp.357-362
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• 2005

중합체의 공액길이를 제어하고 이들이 갖는 에너지 준위를 조절하며, 발광성능향상과 발광파장을 조절하려는 목적으로 설폰기가 포함된 페닐렌-비닐렌계의 새로운 전기발광 고분자들을 Witting 중합을 통해 합성하였다. 합성된 고분자들은 일반 유기 용매에 좋은 용해성을 보였고 $400^{circ}C$ 정도의 초기분해온도와 $200^{circ}C$ 전후의 높은 유리전이온도를 가짐으로써 열적 안정성이 매우 높음을 확인하였다. 각각의 고분자는 용액과 필름상태에서 모두 설폰기의 꺾임에 의해 공액길이가 짧아질수록 UV 흡수와 발광 스펙트럼이 단파장으로 이동하였고 이를 통해 설폰기가 효율적으로 발광파장을 제어하는 것을 확인하였다. 또한 CV측정과 이론적인 계산을 통해 전자친화도가 큰 설폰기에 의해서 합성된 고분자들의 HOMO 및 LUMO 에너지 준위가 상대적으로 낮아짐으로써 소자의 전기발광특성이 향상됨을 확인하였다.

• 대한전기학회논문지:전력기술부문A
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• 제55권10호
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• pp.426-432
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• 2006

This paper describes the concepts of Static Line Rating (SLR) and Dynamic Line Rating (DLR) and the computational methods to demonstrate them. Calculation of the line capacity needs the heat balance equation which is also used for computing the reduced tension in terms of line aging. SLR is calculated with the data from the worst condition of weather throughout the year. Even now, the utilization ratio is obtained from this SLR data in Korea. DLR is the improved method compared to SLR. A process for DLR reveals not only improved line ratings but also more accurate allowed line ratings based on line aging and real time conditions of weather. In order to reflect overhead transmission line aging in DLR, this paper proposes the method that considers the amount of decreased tension since the lines have been installed. Therefore, the continuous allowed temperature for remaining life time is newly acquired. In order to forecast DLR, this paper uses weather forecast models, and applies the concept of Thermal Overload Risk Probability (TORP). Then, the new concept of Dynamic Utilization Ratio (DUR) is defined, replacing Static Utilization Ratio (SUR). For the case study, the two main transmission lines which are responsible for the north bound power flow in the Seoul metropolitan area are chosen for computing line rating and utilization ratio. And then line rating and utilization ratio are analyzed for each transmission line, so that comparison of the present and estimated utilization ratios becomes available. Finally, this paper proves the validity of predictive DUR as the objective index, with simulations of emergency state caused by system outages, overload and so on.

• 한국의류산업학회지
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• 제12권4호
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• pp.531-537
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• 2010

The purpose of this study was to review physiological responses and subjective sensations in the cold environment when the subjects wore ensemble with different clo values. Seven healthy male subjects participated in this experiment. This experiment was conducted in a climatic chamber with $-10^sC$ and 50%RH. Subjects wore five different kinds of ensemble[C1 (4.453 clo), C2 (3.452 clo), C3 (2.865 clo), C4 (2.387 clo), and C5 (2.280 clo)]. The experiment was composed of 20 min of rest period, 20min of treadmill exercise(6 km/h) period, 30 min of recovery period. We monitored skin temperature on 7 sites, clothing microclimate and subjective sensations. The clo value had positive correlations with mean skin temperature and clothing microclimate. The subjects feel more warm and humid as the clo value goes up. The subjects reported comfort when they wore C1 and C2 ensemble having over 3 clo value. However, they felt less comfortable during the exercise period since there was high humidity. Skin temperature on the extremities were more dramatically changed by the exercise rather than clo value. Thus it seems that in the cold environment, heat balance can mostly be controlled by the choice of clothing, and the clothes with high clo values can provide higher insulation. In conclusion, our findings suggest that it would be more effective to control clo value depending on the activity level for maintaining comfort level in the cold environment.

• 농업과학연구
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• 제47권3호
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• pp.683-691
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• 2020

A biomarker is needed to monitor and manage the health of pigs from heat stress (HS). Therefore, we investigated the effects of HS on growth performance, nutrient digestibility, and blood profiles in finishing pigs. A total of 12 finishing pigs (n = 12) were raised in thermal neutral (TN; 25℃) conditions for a 3-d adaptation period. After the adaption, 6 pigs were exposed to HS at 33℃ (HS33) for 5 d. The pigs were fed the same diet based on corn and soybean meal. Chromic oxide was added to all the diets at a level of 2 g·kg^-1 as an indigestible marker for the determination of the apparent total track digestibility (ATTD) of nutrients and amino acids. Blood samples were collected after the adaptation and heat treatment to verify the blood profiles. The HS33 pigs had a lower (p < 0.01) average daily feed intake (ADFI) and higher (p < 0.05) rectal temperature compared to the TN pigs. However, there was no difference in the ATTD of nutrients and amino acids. The HS33 pigs had reduced (p < 0.05) levels of serum glucose, non-esterified fatty acids (NEFA), total protein, albumin, and calcium compared to the TN pigs. However, the level of total bilirubin was increased (p < 0.05) in the HS pigs. In conclusion, HS reduced the feed intake and had an adverse effect on health. Altered blood profiles as a result of a negative energy balance are expected to be biomarkers of HS in finishing pigs.

• Nuclear Engineering and Technology
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• 제36권6호
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• pp.528-539
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• 2004

It is essential in commercial reactors that the safety limits imposed on the fuel pellets and fuel clad barriers, such as the linear power density (LPD) and the departure from nucleate boiling ratio (DNBR), are not violated during reactor operations. In order to accurately monitor the safety limits of current reactor states, a detailed three-dimensional (3D) core power distribution should be estimated from the in-core detector signals. In this paper, we propose a calculation methodology for detailed 3D core power distribution, using in-core detector signals and core monitoring constants such as the 3D Coupling Coefficients (3DCC), node power fraction, and pin-to-node factors. Also, the calculation method for several core safety parameters is introduced. The core monitoring constants for the real core state are promptly provided by the core design code and on-line MASTER (Multi-purpose Analyzer for Static and Transient Effects of Reactors), coupled with the core monitoring program. through the plant computer, core state variables, which include reactor thermal power, control rod bank position, boron concentration, inlet moderator temperature, and flow rate, are supplied as input data for MASTER. MASTER performs the core calculation based on the neutron balance equation and generates several core monitoring constants corresponding to the real core state in addition to the expected core power distribution. The accuracy of the developed method is verified through a comparison with the current CECOR method. Because in all the verification calculation cases the proposed method shows a more conservative value than the best estimated value and a less conservative one than the current CECOR and COLSS methods, it is also confirmed that this method secures a greater operating margin through the simulation of the YGN-3 Cycle-1 core from the viewpoint of the power peaking factor for the LPD and the pseudo hot pin axial power distribution for the DNBR calculation.

• 실천공학교육논문지
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• 제8권2호
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• pp.121-128
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• 2016

사출 성형 공정에서 외관 품질 문제는 대부분의 성형품에서 발생한다. 금형의 열역학적 설계 중의 하나는 어떠한 위치에서 캐비티 표면 온도가 되도록 균일하게 상승하는 것으로 수행된다. 실험적인 평가를 바탕으로 최적의 사출 성형 조건에서 성형품의 미려한 외관 품질을 위해서 캐비티 벽 온도와 다듬질 가공된 캐비티 표면이 성형품의 외관 문제를 피할 수 있는 가장 중요한 요소이다. 또한 잘못된 게이트 형식과 위치 선택은 성형품의 품질에 상당한 영향이 있어서, 각 캐비티로 부터 올바른 러너 밸런스를 유지하는 것은 매우 중요하다. 실질적으로 생산 현장에서 이행될 수 있는 사출 성형 품질을 위한 최적의 금형 설계와 실무 금형 기술 능력 향상을 위해서 현장 교육을 위한 실무적인 금형기술 과정의 교육훈련 모델을 제시하였다.

• 자원리싸이클링
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• 제9권3호
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• pp.13-21
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• 2000

본 연구는 폐용제를 가열, 증발 및 음축과정을 거쳐 용제를 회수하는 시스템의 열교환기 해석에 관한 것으로, 고온 열매체유로 가열되는 이중관형 열교환기를 사용하여 용제 증발과정의 열전달 특성을 분석하고 용제유량과 가열온도에 따라 물, 벤젠 및 알칼벤젠의 증발을 위해 요구되는 전열면적을 분석하였다. 폐용제 회수장치는 용제 공급펌프 이중관형 열교환기, 진공 스프레이 챕버 및 응축기동으로 구성되며, 이중관형 열교환기는 용제액을 열적 포화온도를 가열시키는 구간과 포화된 용제액을 증발시키는 구간으로 구성된다. 관 내 용제의 증발을 위한 전열면적을 열평형 모델링에 의해 예측하였고, 이중관형 열교화기의 관 내 온도분포 측정을 통해 이론값과 비교 분석하였다. 용제유량 0.1~0.51l/mm 및 가열온도 130~$260^{\circ}C$의 범위에서 용제유향 증가 및 가열온도 감속에 따라 단위전열면적당 열전달양이 감소하기 때문에 용제 증발을 위한 전열면적은 증가하였다. 관 내 용제 증발을 위한 전열면적의 이론적 분석결과는 측정값과 일치하였으며, 이중관형 열교환기를 사용한 폐용제의 증발과정을 통해 용제를 회수하는 기술에 적용이 가능하다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.721-727
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• 2002

Precipitation evapotranspiration and runoff are three key parameters of regional water balance. Problems exist in the traditional methods for calculating such factors , such as explaining of the geographic rationality of spatial interpolating methods and lacking of enough observation stations in many important area for bad natural conditions. With the development of modern spatial info-techniques, new efficient shifts arose for traditional studies. Guided by theories on energy flow and materials exchange within Soil-Atmosphere-Plant Continuant (SPAC), retrieval models of key hydrological parameters were established in the Yellow River basin using CMS-5 and FengYun-2 meteorological satellite data. Precipitation and evapotranspiration were then estimated: (1) Estimating tile amount of solar energy that is absorbed by the ground with surface reflectivity, which is measured in the visible wavelength band (VIS): (2) Assessing the partitioning of the absorbed energy between sensible and latent heat with the surface temperature, which was measured in the thermal infrared band (TIR), the latent heat representing the evapotranspiration of water; (3) Clouds are identified and cloud top levels are classified using both VIS and TIR data. Hereafter precipitation will be calculated pixel by pixel with retrieval model. Daily results are first obtained, which are then processed to decade, monthly and yearly products. Precipitation model has been has been and tested with ground truth data; meanwhile, the evapotranspiration result has been verified with Large Aperture Scintillometry (LAS) presented by Wageningen University of the Netherlands. Further studies may concentrate on the application of models, i.e., establish a hydrological model of the Yellow river basin to make the accurate estimation of river volume and even monitor the whole hydrological progress.