• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.604-607
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• 2012

소셜 네트워크 서비스의 하나인 트위터는 팔로우를 통하여 사용자 간의 관계를 맺을 수 있다. 트위터 사용자들은 다양한 팔로워들이 존재한다. 이 팔로워들은 사용자에 대한 호감을 가지고 팔로우 하거나, 맹목적으로 추종하거나, 부정적인 의견을 지니고 사용자의 행동과 글을 관찰하기 위해 팔로우할 수도 있다. 본 논문에서 사용자에게 팔로워들이 어떠한 목적으로 그 사용자를 팔로워의 행태를 분석하는 모델을 제안한다. 대상사용자의 영향력 있는 팔로워를 추출하고, 팔로워의 리트윗 정보, 프로파일, 최신 트윗의 감정분석을 통해 지지자, 중립, 비지지자로 분류한다. 제안 방법의 유효성을 검증하기 위해 트윗 데이터에서 정치인과 언론인 5 명의 팔로워들 중 무작위로 3 만명을 추출하여 실험하였다. 실험 결과 영향력 있는 사용자 추출을 통한 지지 팔로워 추출이 효과적임을 알 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.343-344
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• 2021

최근 영상의 활용도의 증가에 따라, 비정형 영상 데이터에 대한 양이 기하급수적으로 증가하였다. 디지털 영상을 획득할 시에 처리/압축/저장/전송/재생산 등의 과정을 거치면서 왜곡을 수반하게 되며 영상의 품질을 저하시키는 요인이 된다. 영상의 품질은 활용 결과에도 큰 영향을 미치기 때문에 품질이 저하된 영상은 분류를 하는 것이 중요하다. 하지만 사람이 수신된 모든 영상에 대해서 직접 분류를 하는 것은 많은 시간과 비용이 소요된다는 문제점이 존재한다. 따라서 본 논문에서는 사람이 인지하는 주관적인 영상 품질 평가와 유사하게 품질에 대한 평가를 위한 왜곡영상의 특징정보를 검출 및 분석하는 방안에 대해서 제안한다. 본 방법은 사람이 영상을 인지할 때 가장 많이 사용되는 요소인 색상에 대한 선명도, 블러와 노이즈에 대한 특징정보를 이용한다. 검출된 특징정보를 공간 도메인으로 변환함으로써 왜곡 영상별 특성을 분석하였다. 실험을 위해서 IQA 데이터베이스인 LIVE를 이용하였으며, 원본영상 및 5가지 유형의 왜곡영상으로 구성되어 있다. 실험결과 품질이 좋은 영상과 왜곡영상에 대한 특성을 검출할 수 있었다.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.1-8
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• 1996

A one-stage, continuous-flow bioreactor with both immobilized and suspended cells was used to investigate the roles of lipid supplements in ethanol production by Saccharomyces cerevisiae. The reactor performance and the level of alcohol dehydrogenase(ADH) activities of the suspended cells, grown under various conditions, were measured. When ergosterol and/or oleic acid were added with surfactants to the yeast culture grown under non-aerated conditions, remarkable increases in ethanol production and cell growth was achieved, but specific ADH activities were not affected. Especially, no difference of specific ADH activities of the suspended cells grown under aerated and non-aerated condition was observed. The addition of the surfactant as a supplement also resulted in significant increases in ethanol production, cell growth, and specific ADH activity. When ergosterol and oleic acid were added to the yeast culture exposed to higher ethanol concentration($>40\;g/{\ell}$) level, ethanol production, cell growth, and specific ADH activity were increased, but the addition of surfactant was as effective as at lower ethanol concentration level. The results indicated that lipid supplements were more effective at higher ethanol concentration level than at lower ethanol concentration level during ethanol production. ADH isozyme patterns of the yeast cultures grown under various conditions on starch gel electrophoresis showed only one major band, probably ADH I. The migrating distance of the major isozyme, however, varied slightly according to the culture conditions of the cells. No apparent correlation was found between specific ADH activity and amount of ethanol produced. Cell mass was more important factor for ethanol production than specific ADH activity of the cells.

• Geophysics and Geophysical Exploration
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• v.21 no.3
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• pp.150-161
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• 2018

Recently, unmanned aircraft EM (electromagnetic) survey based on ICT (Information and Communication Technology) has been widely utilized because of the efficiency in regional survey. We performed the theoretical study on the unmanned airship EM system developed by KIGAM (Korea Institute of Geoscience and Mineral resources) as part of the practical application of unmanned aircraft EM survey. Since this system has different configurations of transmitting and receiving loops compared to the conventional aircraft EM systems, a new technique is required for the appropriate interpretation of measured responses. Therefore, we proposed a method to calculate the EM field for the arbitrary shaped transmitter and verified its validity through the comparison with analytic solution for circular loop. In addition, to simulate the magnetic responses by three-dimensionally (3D) distributed anomalies, we have adapted our algorithm to 3D frequency-domain EM modeling algorithm based on the edge-FEM (finite element method). Though the analysis on magnetic field responses from a subsurface anomaly, it was found that the response decreases as the depth of the anomaly increases or the flight altitude increases. Also, it was confirmed that the response became smaller as the resistivity of the anomaly increases. However, a nonlinear trend of the out-of-phase component is shown depending on the depth of the anomaly and the used frequency, that makes it difficult to apply simple analysis based on the mapping of the magnitude of the responses and can cause the non-uniqueness problem in calculating the apparent resistivity. Thus, it is a prerequisite to analyze the appropriate frequency band and flight altitude considering the purpose of the survey and the site conditions when conducting a survey using the unmanned aircraft EM system.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.378-383
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• 2001

Formation of superoxide anion $O_2\bar{{\bullet}}$ in the autoxidation of L-ascorbic acid (AsA) in the presence of heavy metal ions were determined. The generation of $O_2\bar{{\bullet}}$ was studied by using superoxide dismutase (SOD) in aqueous and buffer solution, and using nitro bule tetrazolium (NBT) in methanol solution. The remaining amount of AsA was significantly higher in the presence of SOD than in its absence. It suggested that SOD stabilizes AsA in aqueous and buffer solution because of scavenging $O_2\bar{{\bullet}}$ formed during the autoxidation reaction of AsA in the presence of heavy metal ions. NBT has an absorption maximum at about 560 nm in methanol solution. The absorbance at 560 nm increased during the oxidation of AsA, suggested the formation of $O_2\bar{{\bullet}}$in methanol solution. Thus, the formation of $O_2\bar{{\bullet}}$ was confirmed during the autoxidation of AsA not only in aqueous solution but also in methanol solution in the presence heavy metal ions.

• Food Engineering Progress
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• v.22 no.4
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• pp.344-352
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• 2018

The effects of chemical compositions (protein, lipid, and dietary fiber) on the physical properties of dried biji powders were investigated. The raw biji was freeze-dried (control) and hot-air dried (untreated). The untreated biji was further defatted and deproteinated. The prepared biji powders were analyzed for the proximate composition, total dietary fiber (TDF), water absorption index (WAI), water solubility index (WSI), swelling power, solubility (including the quantification of soluble carbohydrate and protein fractions), and final viscosity (using a rapid visco analyzer). Control and untreated biji powders exhibited the similar chemical compositions. The defatted biji possessed higher TDF, although its protein content did not significantly differ for control and untreated ones. The deproteinated biji consisted mainly of TDF. WAI and swelling power increased in the order: deproteinated > defatted > control > untreated biji powders. WSI and solubility increased in the order: control > untreated > defatted > deproteinated biji powders. The similar patterns were observed for soluble carbohydrate and protein fractions. The deproteinated biji revealed the highest viscosity over applied temperatures, while the untreated one was lowest. Overall results suggested that the physical properties of the dried biji powder were reduced by protein and fat, but enhanced by dietary fiber.

• The Korean Journal of Applied Statistics
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• v.20 no.3
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• pp.499-514
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• 2007

It is a common practice to use the auxiliary variables to impute missing values from item nonresponse in surveys. Sometimes there are few auxiliary variables for missing value imputation, but if spatial and time autocorrelations exist, we should use these correlations for better results. Recently, Lee et al. (2006) showed that spatial autocorrelation could be efficiently used for missing value imputation when spatial autocorrelation existed, using the data from the farm household economy data in Gangwon-do, 2002. In this paper, we present au evaluation of spatial and space-time nonresponse imputation methods when there exist spatial and time autocorrelations using the monthly data during 2000-2002 from the same data previously used by Lee et al. (2006). We show that space-time imputation method is more efficient than the other through the numerical simulations.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.31-44
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• 1997

저자들은 악관절내장증의 증상과 징후의 객관적 평가법을 개발하기 위하여 서울대학교치과 병원 구강진단과 악안면동통진료실을 내원한 환자중 좌우 양 관절중 한 관절 이상의 관절에 악관절내장이 있는 남자 8명(평균연령 19.9$\pm$2.9세), 여자 34명(평균연령:32.8$\pm$11.8세) 총 42명(84개 관절)에 대하여 VAS 및 압통역치 측정, 악관절조영술, 골신티그래피 검사 및 악관절 활액의 분석을 시행하였다. 악관절 동통의 심도는 VAS로 측정을 하였으며 PPT는 electronic algometer로 평가를 하였다. 악관절조영사진을 얻기 직전 활액을 채취하였으며 그 성분중 Hyaluronic acid, 총단백질, IgG, IgM과 albumin을 분석하여 그 상관관계를 분석한 결과 다음과 같은 결론을 얻었다. 1. 악관절 내장증으로 내원한 환자 42명, 총 84개 관절중, 무통성이고 관절잡음이 없는 경우가 7개 관절, 무통성이고 단순관절음만 존재하는 경우가 18개 관절, 동통 및 단순관절음이 존재하는 경우가 18개 관절, 간헐적인 폐구 과두걸림이 있는 경우가 11개 관절, 급성 폐구성 과두걸림의 경우가 11개 관절, 만성 폐구성 과두걸림의 경우가 3개 관절, 퇴행성 관절질환이 존재하는 경우가 16개 관절이었다. 2. 연구대상중 18명의 환자, 총 36개 관절에 대한 골 신티그래피 검사 결과, 활동성으로 나타난 경우가 33개 관절이었고 이중 23개 관절이 동통성이었으며, 활동 상태 관절의 VAS 항목과 압통역치 항목 및 여러 검사 항목들은 비활동 상태 관절의 항목과 유의한 차이를 나타내지 않았다. 3. 악관절내장의 진행정도에 따른 악관절부위의 동통의 측정에 있어서는 압통역치의 측정보다는 VAS에 의한 방법이 더 유용하며 특히, 후방부의 촉진시에 유의한 정보를 얻을 수 있었다. 4. 악관절 내장즈으이 진행 단계에 따라, VAS항목과 압통역치 항목을 비교해 본 결고, 주기적인 과두걸림(II) 단계에서 가장 높은 VAS 수치와 가장 낮은 압통역치를 나타내었으며 상방 촉진시 VAS 항목에서 주기적인 과두걸림(II) 단계와 증상 및 징후가 없는(0) 단계 사이와 후방 촉진시 VAS 항목에서 주기적인 과두걸림(II) 단계 및 퇴행성 관절 질환(V) 단계와 증상 및 징후가 없는(0) 단계 사이에서만 유의성을 나타내었다. 5. 활액내 총단백질량, albumin 량, IgG 및 IgM 농도는 악과？ㄹ 내장증의 진행에 따라 유의성을 나타내지는 않았으나 퇴행성 관절 질환(V) 단계에서 증가되는 양상을 나타내었다. 6. 활액내 hyaluronic acid의 농도는 악관절 내장증의 진행에 따라 유의성을 나타내지는 않았으나 만성 폐구성 과두걸림(IV) 단계에서 감소되는 양상을 나타내었다.

• Childhood Kidney Diseases
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• v.3 no.1
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• pp.72-79
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• 1999

Renal scarring associated with vesico-ureteral reflux(VUR) is one of the major causes of end stage renal failure and renal hypertension in children. Urinary ${\beta}_2$-microglobulin(MG) has been suggested as a potential marker for presence of renal tubular damage. This study was designed to evaluate the significance of random urine ${\beta}_2$-MG as a predictor of presence of vesico-ureteral reflux in children with urinary tract infection(UTI). 57 children with urinary tract infection were studied. Patients were devided into two groups; 35($78.9\%$) children have UTI without VUR and 12($21.1\%$) children have UTI and VUR. Beta2-MG and creatinine in random urine sample was measured to decide the excretion ratio(${\beta}_2$-MG/creatinine). Among the 57 children with UTI, 44 children were confirmed by urine culture study and 13 children suspected by compatible clinical feature. Random urine ${\beta}_2$-MG of VUR group ($2.2{\pm}5.91$ mg/L) were significantly higher than that of simple UTI group($0.19{\pm}0.16mg/L$)(P=0.03). The ${\beta}_2$-MG/creatinine ratio of VUR group($32.41{\pm}25.7$) were significantly higher than that of simple UTI group($3.93{\pm}3.44$)(P=0.007). In conclusion, random urine ${\beta}_2$-MG and excretion ratio deserved early predictor of presence of VUR in children with UTI. And this method was more simple and inexpensive than the method of measuring ${\beta}_2$-MG with 24 hour urine collection, so might be a useful screening test for VUR in children with UTI.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.4
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• pp.369-375
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• 2012

In order to overcome the detection limit by the current nondestructive evaluation technology, a nonlinear resonant ultrasound spectroscopy(NRUS) technique was applied for detection of micro-scale cracks in a material. A down-shift of the resonance frequency and a variation of normalized amplitude of the resonance pattern were suggested as the nonlinear parameter for detection of micro-scale cracks in a materials. A natural-like crack were produced in a standard compact tension(CT) specimen by a low cycle fatigue test and the resonance patterns were acquired in each fatigue step. As the exciting voltage increases, a down-shift of resonance frequency were increases as well as the normalized amplitude decrease. This nonlinear effects were significant and even greater in the cracked specimen, but not observed in a intact specimen.