단량체 및 무기질 filler 조성 변화에 따른 복합레진의 유변학적 특성

이인복,이종혁,조병훈,손호현,이상탁,엄정문 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.6

Objectives. The aim of this study was to investigate the effect of monomer and filler compositions on the rheological properties related to the handling characteristics of resin composites. Methods. Resin matrices that Bis-GMA as base monomer was blended with TEGDMA as diluent at various ratio were mixed with the Barium glass (0.7 um and 1.0 um), 0.04 um fumed silica and 0.5 um round silica. All used fillers were silane treated. In order to vary the viscosity of experimental composites, the type and content of incorporated fillers were changed. Using a rheometer, a steady shear test and a dynamic oscillatory shear test were used to evaluate the viscosity (η) of resin matrix, and the storage shear modulus (G′), the loss shear modulus (G″), the loss tangent (tanδ) and the complex viscosity (η*) of the composites as a function of frequency ω= 0.1-100 rad/s. To investigate the effect of temperature on the viscosity of composites, a temperature sweep test was also undertaken. Results. Resin matrices were Newtonian fluid regardless of diluent concentration and all experimental composites exhibited pseudoplastic behavior with increasing shear rate. The viscosity of composites was exponentially increased with increasing filler volume%. In the same filler volume, the smaller the fillers were used, the higher the viscosities were. The effect of filler size on the viscosity was increased with increasing filler content. Increasing filler content reduced tanδby increasing the G′further than the G″. The viscosity of composites was decreased exponentially with increasing temperature.

구치부 복합레진의 적정 RADIOPACITY에 관한 연구

김병현,이정식,엄정문 大韓齒科保存學會 1992 Restorative Dentistry & Endodontics Vol.17 No.1

The aim of this study was to compare the accuracy of radiographic diagnosis of secondary carious lesions adjacent to composite filling materials with different radiopacity. The level of radiopacity that is most compatible with the radiographic diagnosis of secondary caries was studied in a two part experiment. In the first part, the radiopacity of 6 posterior composites (BP, CF, HM, LF, PQ, P50), enamel and dentin were measured by desitometer and 6 posterior composites divided into 3 groups based on their level of radiopacity compared with enamel and dentin. In the second part, class II composite fillings with or without secondary caries were made in extracted premolar and radiographs of the teeth were examined by 10 dentists to diagnose simulated carious lesion. The following results were obtained : 1. The radiopacity of 6 posterior composites varied between 1.76(PQ) and 6.78(P50)mm Al equivalent. 2. For 4 composites the radiopacity exeeded that of an equal thickness of enamel, and for two the radiopacity was lower than that of dentin. 3. The detection of secondary caries was facillitated when the radiopacity of a composite resin was similar to or slightly greater than that of enamel.

수직 진동형 Rheometer를 이용한 복합레진의 유변학적 성질의 측정

이인복,조병훈,손호현,이상탁,엄정문 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.6

Objective: The purpose of this study was to investigate the viscoelastic properties related to handling characteristics of composite resins. Methods: A custom designed vertical oscillation rheometer (VOR) was used for rheological measurements of composites. The VOR consists of three parts: (1) a measuring unit, (2) a deformation induction unit and (3) a force detecting unit. Two medium viscous composites, Z100 and Z250 and two packable composites, P60 and SureFil were tested. The viscoelastic material function, including complex modulus E* and phase angle δ, were measured. A dynamic oscillatory test was used to evaluate the storage modulus (E′), loss modulus (E″) and loss tangent (tanδ) of the composites as a function of frequency (ω) from 0.1 to 20 ㎐ at 23℃. Results: The E′and E″ increased with increasing frequency and showed differences in magnitude between brands. The E*s of composites at ω= 2 ㎐, normalized to that of Z100, were 2.16 (Z250), 4.80 (P60) and 25.21 (SureFil). The magnitudes and patterns of the change of tanδof composites with increasing frequency were significantly different between brands. The relationships between the complex modulus E*, the phase angle δ and the frequency ωwere represented by frequency domain phasor form, E* (ω) = E*e^(iδ)= E*∠δ. Conclusions: The viscoelasticity of composites that influences handling characteristics is significant different between brands. The VOR is a relatively simple device for dynamic, mechanical analysis of high viscous dental composites. The locus of frequency domain phasor plots in a complex plane is a valuable method of representing the viscoelastic properties of composites.

자연환경방사선에 의한 피폭선량(유효선량당량)의 종합적 해석연구

전재식,채하석,이병영,김현창,이동준,김도성,엄두하 충남대학교 기초과학연구소 1990 연구논문집 Vol.10 No.-

자연환경방사선의 세 가지 주요 요소인 지각방사선, 우주선 전리성분 및 라돈과 그 자핵종이 주는 선량을 측정, 해석하였는 바 18개월간에 걸쳐 대전, 수원, 경산 지역에 대하여 수행하고 이를 종합하여 유효선량당량으로 평가하였다. 지각방사선과 우주선 전리성분 측정을 위하여 3"∮×3" Nal(Tl) 섬광검출기와 휴대형 다중파고분석기를 이용한 감마선 분광분석 및 ^7LiF PTEE disk TLD에 의한 적산선량측정을 병행하였고, 공기중 라돈농도의 측정은 CR-39 고체비적검출기를 내장한 라돈컵을 설계제작하여 사용하였으며 비적수 라돈농도 교정인자는 스웨덴 국립방사선 방호연구소의 표준 라돈 챔버내에서 조사하여 결정하였다. 세 지역의 가연방사선에 의한 유효선량당량에는 약간의 수치적 차이는 있었으나 본질적 차이는 찾아볼 수 없었으며 지역 측정치의 분산가중 평균치는 지각방사선 (463±3)uSvㆍy^-1[(52.9±0.3)nSvㆍh^-1], 우주선 전리성분 (287±15)uSvㆍy^-1[(32.8±1.7)nSvㆍy^-1]로 외부 피폭이 (775±9)uSvㆍy^-1[(88.5±1.0)nSvㆍy^-1]였으며 라돈과 그 자핵종에 의한 내부피폭은 (1973±298)uSvㆍy^-1[(225.2±34.0)nSvㆍy^-1]였다. 따라서 자연황경방사선에 의한 여간 총 선량당량은 (2762±296)uSvㆍy^-1[(315.3±34.0)nSvㆍh^-1]로 평가되었는데 이 값들은 UN보고서^(11)에 나온 “정상적 자연방사선 지역”의 값과 비교할 만한 타당한 값으로 나타났다. Assessment of effective dose equivalent from natural environmental radiation that consists of terrestrial gamma­ray, ionizing component of cosmic­ray and alpha­rays of atmospheric radon and its decay products has been carried out for 18 months in Daejeon, Suwon and Kyungsan areas. A 3"∮×3"cylindrical Nal(Ti) scintillation detector in association with portable multichannel analyser and ^7LiF PTFE disk TLDs were used for the measurement of terrestrial gamma­ray and cosmic­ray ionizing component, while self­designed radon­cups with CR-39 SSNTD attached to the inside bottom were used for the integral measurement of at­mospheric radon concentration. Determination of calibration factor for converting track density of CR-39 detector to radon concentration was made by irradiation of radon­cups in the standard radon chamber of Swedish National Institute of Radiation Protection. Although resultant effective dose equivalents of three different measurment points show minor numerical differences, no essential discripancy between the places was found. The variance weighted means of the annual effective dose equivalents of each component of radiation from the tree places came out to be: (463±3)uSvㆍy^-1[(52.9±0.3)nSvㆍy^-1] for terrestrial gamma­ray, (287±15)uSvㆍy^-1[(32.8±1.7)nSvㆍy^-1] for ionizing component of cosmic­ray and (1973±298)uSvㆍy^-1[(225.2±34.0)nSvㆍy^-1] for internal exposure of radon and its decay products. Consequent total effective dose equivalent turned out to be (2762±298)uSvㆍy^-1[(315.3±34.0)nSvㆍy^-1], which if reasonably comparable with that appeared in UNSCEAR Report^[11]as per caput annual effective dose equivalent in “areas of normal back ground radiation.”

Protection of Surgical Team from COVID-19 during Bipolar Hemiarthroplasty in an Infected Elderly Patient

Sang-Hyun Um,Du-Han Kim,Moon-Yul Youn,Chul-Hyun Cho,Hyun-Ah Kim,Byung-Woo Min,Ki-Cheor Bae,Kyung-Jae Lee 대한정형외과학회 2020 Clinics in Orthopedic Surgery Vol.12 No.3

The novel coronavirus disease 2019 (COVID-19), which began in Wuhan, China, has rapidly flared up all over the world, evolving into a pandemic. During these critical times, we should give emphasis on infection prevention for the health care staff as well as appropriate patient management in order to maintain the health care system. We report our experience in protecting a surgical team from COVID-19 infection during a bipolar hemiarthroplasty in an infected patient. This case highlights the importance of appropriate protection of the health care staff and education in minimizing the risk of transmission of the infection and maintaining the health care system.

장기간연속수수량추정모형(長期間連續受水量推定模型)의 실용화(實用化) 연구(硏究) -우리나라 중소유역(中小流域)을 대상(對象)으로-

임병현 ( Um Byung Hyun ) 한국농공학회 1990 韓國農工學會誌 : 전원과 자원 Vol.32 No.4

This study aimed at developing a generalized model on the estimation of the long - term run - off volume for practical purpose. During the research period of last 3 years( 1986-1988), 3 types of estimation model on the long - term run - off volume(Effective rainfall model, unit hydrograph model and barne's model for dry season) had been developed by the author. In this study, through regressional analysis between determinant factors (bi of effective rainfall model, ai of unit hydrograph model and Wi of barne's model) and catchment characteris- tics(catchment area, distance round the catchment area, massing degree coefficient, river - exte- nsion, river - slope, river - density, infiltration of Watershed) of 11 test case areas by multiple regressional method, a new methodology on the derivation of determinant factors from catchment characteristics in the watershed areas having no hydrological station was developed. Therefore, in the resulting step, estimation equations on run - off volume for practical purpose of which input facor is only rainfall were developed. In the next stage, the derived equations were applied on the Kang - and Namgye - river catchment areas for checking of their goodness. The test results were as follows ; 1. In Kang - river area, average relative estimation errors of 72 hydrographs and of continuous daily run - off volume for 245 days( 1/5/1982 - 31/12) were calculated as 6.09%, 9.58% respectively. 2. In Namgye - river area, average relative estimation errors of 65 hydrographs and of conti-nuous daily run - off volume for 2fl days(5/4/1980-31/12) were 5.68%, 10.5% respectively. In both cases, relative estimation error was averaged as 7.96%, and so, the methodology in this study might be hetter organized than Kaziyama's formula when comparing with the relative error of the latter, 24~54%. However, two case studies cannot be the base materials enough for the full generalization of the model. So, in the future studies, many test case studies of this model should he carries out in the various catchment areas for making its generalization.

A Novel Transmitter and Receiver Structure for Cognitive Radio Based OFDM Systems

UM, Jung-Sun,HWANG, Sung-Hyun,KIM, Chang-Joo,JEONG, Byung Jang The Institute of Electronics, Information and Comm 2011 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb94 No.4

<P>Wireless regional area network (WRAN) is intended to offer the fixed wireless access services using cognitive radio technology in the TV white space. Therefore, WRAN shall minimize the transmission power so that harmful interference is not imposed on the licensed users operating in the TV bands. In this paper, we propose a processing block that offers improvements in the SNR and diversity gain using the block to algebraically process two constellation symbols. Thus, the transmission power can be reduced by an amount equal to the gains. The simulation result shows that the proposed scheme has a better bit error performance than the transmission scheme defined in the IEEE 802.22 draft standard.</P>

Increased and correlated nuclear factor-kappa B and Ku autoantigen activities are associated with development of multidrug resistance

Um, Jee Hyun,Kang, Chi Dug,Lee, Bok Gun,Kim, Dong Wan,Chung, Byung Seon,Kim, Sun Hee 부산대학교 유전공학연구소 2001 분자생물학 연구보 Vol.17 No.-

In this syudy, we investigated possible engagement of NF-κB and Ku autoantigen (Ku) activation in development of multidrug resistance (MDR) and circumvention of MDR by modulation of NF-κB and Ku. The NF-κB activity and NF-κB p65 subunit level were constitutively higher in MDR cells than in drug-sensitive parental cells. Interestingly, a faster running NF-κB DNA binding complex was identified as Ku, a DNA binding complex was identified as Ku, a DNA damage sensor and a key double strand break repair protein, and was positively correlated with the NF-κB-transfected cells. Also both NF-κB and Ku activities were activated or inhibited by treatment with etoposide (VP-16) MG-132 (a proteasome inhibitor), respectively. Furthermore, PKA inhibitor suppressed markedly the constitutive and drug-induced activities of NF-κB and Ku in MDR cells and subsequently potentiated the cytotoxic activity of antivancer drugs. Our results proposed that the NF-κB and Ku activation could be one of multi-factorial MDR mechanism, and PKA inhibitor, likely via inhibition of NF-κB and Ku activities, could enhance the effectiveness of anticancer drugs against MDR cells with high activities of NF-κB and Ku. Oncogene (2001) 20, 6048-6056.

Hydrogen Production by a New Strain, Clostridium aurantibutyricum FH2072, using Food Waste

Byung-Chun KIM,Hyun-Ju OH,Kyung Yee SOHN,Youngsoon Um,Se Il KIM,Jong Sik CHUN,Byoung-In SANG 한국생물공학회 2009 한국생물공학회 학술대회 Vol.2009 No.4

Incidentally Detected Asymptomatic Perianal Abscess in an Adolescent during Crohn's Disease Diagnosis: Is Routine Pelvic Imaging Required in Korean Pediatric Patients at Diagnosis?

Um, Soo Hyun,Lee, Sang Woo,Song, Ki Hwan,Lee, So Mi,Choe, Byung-Ho,Lee, Yoo Min,Kang, Ben The Korean Society of Pediatric Gastroenterology 2021 Pediatric gastroenterology, hepatology & nutrition Vol.24 No.6

Perianal fistulizing diseases, namely perianal fistulas and/or abscesses, are well-known complications of Crohn's disease (CD). These are known to develop more frequently in Asian children with CD, especially in the early stages of the disease course. Approximately half of the pediatric CD cases in Korea present with perianal fistulizing diseases at diagnosis. We report a rare case of a 12-year-old boy with CD with an incidental discovery of a perianal abscess on pelvic magnetic resonance imaging during CD diagnosis. No symptoms or signs of perianal fistulizing disease were identified. The early diagnosis of the perianal abscess enabled timely and effective treatment. Considering the high incidence of concomitant perianal CD in Korean children at diagnosis, perianal imaging may be useful and should be considered during diagnostic evaluation, even in patients with no subjective or objective findings indicating perianal CD.