• 한국전자파학회논문지
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• 제17권5호
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• pp.408-415
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• 2006

본 논문에서는 RF 전력 증폭기의 메모리 효과를 모델링하기 위한 향상된 시스템 레벨의 모델을 제안하고, 사전 왜곡 선형화기를 적용한 전력 증폭기의 출력 신호의 스팩트럼 밀도를 분석하여 제안한 모델을 검증하였다. 기존의 Three-Box(Wiener-Hammerstein) 모델은 전력 증폭기의 RF 주파수 특성을 입출력 선형 필터를 사용하여 모델링한 것으로, Hammerstein 구조의 사전 왜곡 선형화기를 사용하면 이론적으로 인접 채널 간섭을 모두 제거할 수 있다. 그러나, 실제 전력 증폭기의 경우 RF 주파수 특성 외의 메모리 현상에 의해 주파수 특성만을 보정한 Hammerstein 사전 왜곡기에 의한 인접 채널 간섭비의 향상 정도가 제한적이다. 이러한 출력 스팩트럼 특성은 Three-Box 모델의 메모리 성분을 가지지 않는 비선형 블록을 메모리 다항식으로 바꾸어 준 모델을 사용하여 정확히 예측될 수 있다. IEEE 802.11 g 무선 랜 전력 증폭기에 Hammerstein 구조의 사전 왜곡이 적용된 경우 측정된 인접 채널 스팩트럼 밀도값을 제안된 모델은 ${\pm}30$ MHz의 인접 채널 범위에서 2 dB 이하의 오차로 예측하였다.

• 한국양식학회지
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• 제16권1호
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• pp.1-7
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• 2003

무지개송어의 대동맥에 삽입관을 부착한 후 스트레스와 관련된 생리화학적 반응을 조사하였고, 실험사료의 위내 강제공급 후 혈장내 유리 아미노산의 농도변화를 비교하였다. 무지개 송어에 있어 아미노산의 요구량 설정 모델 개발을 위한 기초연구로서 사료 영양학적 연구를 위한 새로운 사료공급 및 혈액채취 방법의 개발을 위하여, 강제투여 및 대동맥 삽입방법의 적용 가능성을 조사하였다. 스트레스와 관련된 생리화학적 반응조사에 있어서 혈액내 헤마토크리트(Ht)는 6시간에 최대치를 보였고, 12시간에 최초수준으로 돌아와 48시간까지 유지되었고 혈장내 코티졸과 글루코스는 3시간에 증가하기 시작하여 6시간에 최대치를 보였으며(P<0.05), 48시간에 최초수준으로 돌아왔다. 혈장내 총 단백질 함량, 삼투압, Na농도, K농도, Cl농도, 헤모글로빈(Hb)수와 적혈구수(red blood cell, RBC)는 48시간동안 큰 변화를 보이지 않았다. 실험사료의 위내 강제 공급 후 혈장내 유리 아미노산의 농도 변화는, arginine, histidine, Iysine, methionine, threonine. valine, glutamic acid. isoleucine, leucine, phenylalanine과 tryptophan이 사료공급 후 4시간에 최대치를 보였고, 8~24시간사이에 최초수준 또는 감소하고, 48시간까지 일정하게 유지되었다. glycine은 사료공급 후 4~8사이에 감소하여 12시간에 최대치를 보였고 24시간에 최초수준으로 돌아왔다. alanine과 aspartic acid의 농도는 사료공급 후 4시간에 최대치를 보였고, 48시간에 기본농도로 돌아왔다. 상기 결과를 토대로, 위내 강제 공급 방법과 대동맥 삽입방법을 무지개 송어의 사료 영양학적 연구에 적용 가능하였고, 유리아미노산의 농도 측정으로 필수 아미노산 요구량 추정이 가능함을 보여주었다.

• 한국환경보건학회지
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• 제45권1호
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• pp.1-8
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• 2019

Objectives: The purpose of this study was to estimate the ventilation rate of residential homes in Korea through tracer gas methods using indoor and outdoor concentrations of carbon dioxide ($CO_2$) and $CO_2$ generation rates from breathing. Methods: In this study, we calculated the number of occupants in a home by time through data on the average number of people per household from the Korean National Statistical Office and also measured the amount of $CO_2$ generation by breathing to estimate the indoor $CO_2$ generation rate. To estimate the ventilation rate, several factors such as the $CO_2$ generation rate and average volume of residential house provided by the Korean National Statistical Office, indoor $CO_2$ concentrations measured by sensors, and outdoor $CO_2$ concentrations provided by the Korea Meteorological Administration, were applied to a mass balance model for residential indoor environments. Results: The average number of people were 2.53 per household and Koreans spend 61.0% of their day at home. The $CO_2$ generation rate from breathing was $13.9{\pm}5.3L/h$ during sleep and $15.1{\pm}5.7L/h$ in a sedentary state. Indoor and outdoor $CO_2$ concentrations were 849 ppm and 407 ppm, respectively. The ventilation rate in Korean residential houses calculated by the mass balance model were $42.1m^3/h$ and 0.71 air change per hour. Conclusions: The estimated ventilation rate tended to increase with an increase in the number of occupants. Since sensor devices were used to collect data, sustainable data could be collected to estimate the ventilation rate of Korean residential homes, which enables further studies such as on changes in the ventilation rate by season resulting from the activities of occupants. The results of this study could be used as a basis for exposure and risk assessment modeling.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.27-33
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• 1995

A time-dependent large deformation fracture theory is developed for application to soft biological tissues. The theory uses the quasilinear viscoelastic theory of Fung, and particularizes it to constitutive assumptions on polyvinyl-chloride (PVC) (Part I) and cartilage (Part II). This constitutive theory is used in a general viscoelastic theory by Christensen and Naghdi and an energy balance to develop an expression for the fracture toughness of the materials. Experimental methods are developed for measuring the required constitutive parameters and fracture data for the materials. Elastic stress and reduced relaxation functions were determined using tensile and shear tests at high loading rates with rise times of 25-30 msec, and test times of 150 sec. The developed method was validated, using an engineering material, PVC to separate the error in the testing method from the inherent variation of the biological tissues. It was found that the the proposed constitutive modeling can predict the nonlinear stress-strain and the time-dependent behavior of the material. As an approximation method, a pseudo-elastic theory using the J-integral concept, assuming that the material is a time-independent large deformation elastic material, was also developed and compared with the time-dependent fracture theory. For PVC. the predicted fracture toughness is $1.2{\pm}0.41$ and $1.5{\pm}0.23\;kN/m$ for the time-dependent theory and the pseudo-elastic theory, respectively. The methods should be of value in quantifying fracture properties of soft biological tissues. In Part II, an application of the developed method to a biological soft tissue was made by using bovine humeral articular cartilage.

• 한국환경과학회지
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• 제22권7호
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• pp.823-836
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• 2013

Emissions of air pollutants and greenhouse gases (GHGs) from aircraft activities at 11 small-scale airports were investigated using the emissions and dispersion modeling system (EDMS) version 5.1.3 during the two year period of 2009~2010. The number of landing and take-off (LTO) at these airports was dominant for the aircraft type B737, accounting for more than 60% of the total LTOs. Out of the 11 small-scale airports, Gwangju (GJ, RKJJ) airport was the largest emitter of air pollutants and GHGs, whereas Yangyang (YY, RKNY) airport was the smallest emitter. The emissions of $NO_x$ and VOCs in 2010 at the 11 airports ranged from 1.9 to 83 ton/y and 0.1 to 17 ton/y, respectively. In 2010, the emissions of $CO_2$ ranged from 394 to 21,217 ton/y. The emissions of most air pollutants (except for $NO_x$ and $PM_{10}$) and GHGs were estimated to be the highest in taxi-out mode. The highest emissions of $NO_x$ and $PM_{10}$ were emitted from climb-out and approach modes, respectively. In addition, the total LTOs at the 11 small-scale airports accounted for the range of 9.3~9.9% of those at four major international airports in Korea. The total emissions of air pollutants and GHGs at the 11 airports ranged from 4.8 to 12% of those at the four major airports.

• 한국환경과학회지
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• 제19권5호
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• pp.591-605
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• 2010

This study were to simulate major criteria air pollutants and estimate regional source-receptor relationship using air quality prediction model (TAPM ; The Air Pollution Model) in the Seoul Metropolitan area. Source-receptor relationship was estimated by contribution of each region to other regions and region itself through dividing the Seoul metropolitan area into five regions. According to administrative boundary, region I and region II were Seoul and Incheon in order. Gyeonggi was divided into three regions by directions like southern(region III), northern(IV) and eastern(V) area. Gridded emissions ($1km{\times}1km$) by Clean Air Pollicy Support System (CAPSS) of National Institute of Environmental Research (NIER) was prepared for TAPM simulation. The operational weather prediction system, Regional Data Assimilation and Prediction System (RDAPS) operated by the Korean Meteorology Administration (KMA) was used for the regional weather forecasting with 30km grid resolution. Modeling period was 5 continuous days for each season with non-precipitation. The results showed that region I was the most air-polluted area and it was 3~4 times more polluted region than other regions for $NO_2$, $SO_2$ and PM10. Contributions of $SO_2$ $NO_2$ and PM10 to region I, II and III were more than 50 percent for their own sources. However region IV and V were mostly affected by sources of region I, II and III. When emissions of all regions were assumed to reduce 10 and 20 percent separately, air pollution of each region was reduced linearly and the contributions of reduction scenario were similar to those of base case. As input emissions were reduced according to different ratio - region I 40 percent, region II and III 20 percent, region IV and V 10 percent, air pollutions of region I and III were decreased remarkably. The contributions to region I, II, III were also reduced for their own sources. However, region I, II and III affected more regions IV and V. Shortly, graded reduction of emission could be more effective to control air pollution in emission imbalanced area.

• 환경영향평가
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• 제29권4호
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• pp.272-285
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• 2020

본 연구에서는 3차원 기상 및 대기질 모델의 입출력 자료를 평가하는 데 필요한 통계 검증지표를 선별하고, 선정된 검증지표의 기준치를 조사하여 그 결과를 요약하였다. 여러 국내외 문헌과 최근 논문 검토를 통해 최종 선정된 통계 검증지표는 MB (Mean Bias), ME (Mean Error), MNB (Mean Normalized Bias Error), MNE (Mean Absolute Gross Error), RMSE (Root Mean Square Error), IOA (Index of Agreement), R (Correlation Coefficient), FE (Fractional Error), FB (Fractional Bias)로 총 9가지이며, 국내외 문헌을 통해 그 기준치를 확인하였다. 그 결과, 기상모델의 경우 대부분 MB와 ME가 주요 지표로 사용되어 왔고, 대기질 모델 결과는 NMB와 NME 지표가 주로 사용되었으며, 그 기준치의 차이를 분석하였다. 아울러 이들 통계 검증지표값을 이용하여 모델 예측 결과를 효과적으로 비교하기 위한 표출 도식으로 축구 도식, 테일러 도식, Q-Q (Quantile-Quantile) 도식의 장단점을 분석하였다. 나아가 본 연구 결과를 기반으로 우리나라의 산악지역의 특수성 등이 잘 고려된 통계 검증지표의 기준치 설정 등의 추가연구가 효과적으로 진행될 수 있기를 기대한다.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.397-409
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• 2007

Owing to needs of biomechanical comprehension and analysis to obtain various medical treatment designs which are related with the spine in order to cure and diagnose LBP patients, the FE modeling and nonlinear analysis of lumbosacrum including a partial ilium and iliolumbar ligaments, were carried out. First, we investigated whether the geometrical configuration of vertebrae displayed by DICOM slice files is regular and normal condition. After constructing spinal vertebrae including a partial ilium, a sacrum and five lumbars (from L1 to L5)with anatomical shape reconstructed using softwares such as image modeler and CAD modeler, we added iliolumbar ligaments, lumbar ligaments, discs and facet joints, etc.. And also, we assigned material property and discretized the model using proper finite element types, thus it was completely modeled through the above procedure. For the verification of each segment, average sagittal ROM, average coronal ROM and average transversal ROM under various loading conditions(${\pm}10Nm$), average vertical displacement under compression(400N), ALL(Anterior Longitudinal Ligament) and PLL(Posterior Longitudinal Ligament) force at L12 level, strains of seven ligaments on sagittal plane at L45 level and maximal strain of disc fibers according to various loading conditions at L45 level, etc., they were compared with experimental results. For the verification of multilevel-lumbosacrum spine including partial ilium and iliolumbar ligaments, the cases with and without iliolumbar ligaments were compared with ROM of experiment. The results were obtained from analysis of the verified FE model as follows: I) Iliolumbar ligaments played a stabilizing role as mainly posterior iliolumbar ligaments under flexion and as both posterior and anterior iliolumbar ligaments of one side under lateral bending. 2) The iliolumbar ligaments decreased total ROM of 1-8% in total model according to various motion conditions, which changed facet contact forces of L5S level by approximately 0.8-1.4 times and disc forces of L5S level by approximately 0.8-1.5 times more than casewithout ilioligaments, under various loading conditions. 3) The force of lower discs such as L45 and L5S was bigger than upper discs under flexion, left and right bending and left and right twisting, except extension. 4) It was predicted that strains of posterior ligaments among iliolumbar ligaments would produce the maximum 16% under flexion and the maximum 10% under twisting. 5) It's expected that this present model applies to the development and design of artificial disc, since it was comparatively in agreement with the experimental datum.

• 한국환경과학회지
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• 제18권2호
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• pp.129-139
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• 2009

Development of an artificial neural network model was presented to predict the daily maximum $SO_2$ concentration in the urban-industrial area of Ulsan. The network model was trained during April through September for 2000-2005 using $SO_2$ potential parameters estimated from meteorological and air quality data which are closely related to daily maximum $SO_2$ concentrations. Meteorological data were obtained from regional modeling results, upper air soundings and surface field measurements and were then used to create the $SO_2$ potential parameters such as synoptic conditions, mixing heights, atmospheric stabilities, and surface conditions. In particular, two-stage clustering techniques were used to identify potential index representing major synoptic conditions associated with high $SO_2$ concentration. Two neural network models were developed and tested in different conditions for prediction: the first model was set up to predict daily maximum $SO_2$ at 5 PM on the previous day, and the second was 10 AM for a given forecast day using an additional potential factors related with urban emissions in the early morning. The results showed that the developed models can predict the daily maximum $SO_2$ concentrations with good simulation accuracy of 87% and 96% for the first and second model. respectively, but the limitation of predictive capability was found at a higher or lower concentrations. The increased accuracy for the second model demonstrates that improvements can be made by utilizing more recent air quality data for initialization of the model.

• Molecules and Cells
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• 제23권2호
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• pp.228-238
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• 2007

Since molecular structure of hnRNP is not available in foreseeable future, it is best to construct a working model for hnRNP structure. A geometric problem, assembly of $700{\pm}20$ nucleotides with 48 proteins, is visualized by a frame work in which all the proteins participate in primary binding, followed by secondary, tertiary and quaternary binding with neighboring proteins without additional import. Thus, 40S hnRNP contains crown-like secondary structure (48 stemloops) and appearance of 6 petal (octamers) rose-like architectures. The proteins are wrapped by RNA. Co-transcriptional folding for RNP fibril of FMR1 gene can produce 2,571 stem-loops with frequency of 1 stem-loop/15.3 nucleotides and 53 40S hnRNP beaded structure. By spliceosome driven reactions, there occurs removal of 16 separate lariated RNPs, joining 17 separate beaded exonic structures and anchoring EJC on each exon junction. Skipping exon 12 has 5'GU, 3'AG and very compact folding pattern with frequency of 1 stem-loop per 12 nucleotides in short exon length (63 nucleotides). 5' end of exon 12 contains SS (Splicing Silencer) element of UAGGU. In exons 10, 15 and 17 where both regular and alternative splice sites exist, SS (hnRNP A1 binding site) is observed at the regular splicing site. End products are mature FMR-1 mRNP, 4 species of Pri-microRNAs derived from introns 7,9,15 and 3'UTR of exon17, respectively. There may also be some other regulatory RNAs containing ALU/Line elements as well.