• 한국전기전자재료학회논문지
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• 제36권2호
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• pp.191-196
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• 2023

In this paper, for the application of ultrasonic cleaners for cleaning dentures and transparent braces, Pb(Mn_1/3Nb_2/3)O₃-Pb(Ni_1/3 Nb_2/3)O₃-Pb(Zr,Ti)O₃ [PMN-PNN-PZT] system ceramics were manufactured and their dielectric and piezoelectric properties were investigated. Overall the best properties suitable for the device applications such as ultrasonic cleaner were obtained from the ceramics sintered at 920℃: bulk density of 7.8 g/cm³, the dielectric constant (ε_r) of 1,689, piezoelectric charge constant (d₃₃) of 433 pC/N, planar electromechanical coupling factor (k_p) of 0.64, mechanical quality factor (Qm) of 835, S₁₁^E of 13.37 (10^-12 N/m²), and Curie temperature of 315℃ By using the physical properties of this composition, the ultrasonic cleaner was designed and simulated using the commercial ATILA software. For the three-layered ceramics with the dimension of 25 mm × 25 mm × 2.5mm, an excellent displacement of 8.998 10^-3 m) and the sound pressure of 147.68 dB were recorded.

• Restorative Dentistry and Endodontics
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• 제47권4호
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• pp.43.1-43.13
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• 2022

Objectives: This study compared the surface gloss (SG), gloss retention (GR), and color stability (CS) of 2 universal resin composites after chemical (CA) and mechanical (MA) aging. Materials and Methods: Twenty disc-shaped samples of G-ænial A'Chord (GC-Europe) and Filtek Universal (3M-ESPE) were polished with sequential abrasive papers. For CA, specimens were stored in 1 mL of 75% ethanol for 15 days at 37℃, and readings (SG, GR, and CS) were obtained at baseline and 5, 10, and 15 days. For MA, specimens were subjected to 10,750 simulated brushing cycles. SG and CS were evaluated after every 3,583 cycles. SG was measured with a glossmeter (geometrical configuration: 60°), and values were expressed in gloss units. Color was measured with a spectrophotometer using the CIE-L^*a^*b^* color system. The Student's t-test, 1-way analysis of variance, and Scheffé test were used for statistical analysis (α = 0.05). Results: G-ænial presented significantly higher SG values than Filtek (p = 0.02), with GR reductions of 5.2% (CA) and 5.3% (MA) for G-ænial and 7.6% (CA) and 7.2% (MA) for Filtek. The aging protocol had no statistically significant effect on SG or GR (p = 0.25) from baseline to the final readings. G-ænial-MA presented the lowest color difference (ΔE = 1.8), and G-ænial-CA and Filtek-CA had the largest changes (ΔE = 8.6 and ΔE = 11.8, respectively). Conclusion: G-ænial presented higher SG values and better CS. Both restorative materials demonstrated acceptable GR and CS. Aging protocols impacted these properties negatively.

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.299-305
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• 2003

Physical properties and microstructure of new coumarin 4 doped $SiO_2$-PDMS ORMOSILs, synthesized by one-step (OS, acid-catalysis) and two-step (TS, acid-base catalysis) routes of sol-gel method with varying pH (0.6 to 7) and dye content $(5\;{times}\;10^{-4}\;to\;5{\times}\;10^{-2}\;mole)$, are reported. BET, UV-visible spectroscopy and SEM were used for characterizations. The increase in acid or base concentration increased the size of pores and aggregated silica particles. The samples with pH ≤ 2.5 were transparent and attributed to the small size of pores (~20 Å) and silica particles. The samples with pH > 2.5 were translucent or opaque due to non-uniform pore system formed by voids and large aggregated silica particles. The surface area was found a key factor controlling the interactions between the gel matrix and the dye. The OS samples with the highest dye concentration exhibited the minimal values of pore size, surface area and silica particle size, resulting in the concentration-quenching phenomenon.

• 한국응용곤충학회지
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• 제35권4호
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• pp.321-325
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• 1996

누에에서 새로운 항세균성 펩타이드 유전자를 탐색하기 위하여 E. coli K12로 체강 주사한 누에 유충의 cDNA 유전자 은행에서 차별화 선별로, 잠재 항세균성 펩타이드 유전자로 추정되는 BmInc8 클론을 분리하였다. BmInc8은 564bp의 크기를 가지며, 59개 아미노산을 coding하는 open reading frame과 2개의 잠정 폴리아데닐화 부위를 보유하고 있었다. BmInc8은 M. sexta에서 분리, 보고된 bactericidine 유전자와 61.2%의 DNA 상동성을 나타내는 것으로, 그 연역된 펩타이드 구조는 항세균성 펩타이드의 일종인 cecropin과 유사한 2가닥의 $\alpha$-helix가 Lysine-Proline 경첩부위에 의해 포개져 있는 형태를 갖는 것으로 추정되었다. 또한 cDNA 삽입 부위의 기능성 검정을 위해 원핵 발현벡터인 pT7-5를 이용하여 E. coli BL21(DE3) 균주에 형질전환하고 IPTG로 induction한 결과 E. coli BL21(DE3) 균주의 성장이 정지됨을 관찰할 수 있었다. 이상의 결과로 BmInc8은 DNA 상동성 비교, 연역 아미노산의 구조 추정 및 cDNA 삽입 부위를 이용한 transient expression 결과 항세균성 펩타이드를 coding하는 유전자임을 추정할 수 있었다. 또한 Bminc8의 cDNA 유전자 정보를 GenBank에 등록하였으며 등록 번호는 U30289이었다.

• 한국대기환경학회지
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• 제23권2호
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• pp.183-190
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• 2007

In this study, we have investigated waste incinerators which are one of the major HAPs emission sources. In order to obtain more reliable HAPs emission data from waste incinerators, direct sampling for the possible pollutants from the stack was carried out and the analysis was performed. The purpose of study was to understand the emission status from waste incinerators and recognize the problems and finally to set up a strategy to reduce the HAPs emissions from waste incinerators. The emission concentrations of 8 species of heavy metals and 16 species of PAHs have been analyzed for the first time in Korea. Not only the emission characteristics of HAPs from waste incinerators were identified, but also the analysis of reduction efficiencies for control devices such as BF and wet scrubbing systems was carried out.

• 생명과학회지
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• 제9권3호
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• pp.253-261
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• 1999

Leptin gene, an obesity gene, has been known to involve in the regulation of food intake and body weight. It is also thought to be related to the glucose metabolism, insulin secretion and type II diabetes mellitus. Recently, the production of recombinant leptin protein has been attempted for the application in the treatment of obesity and the correction of hereditary obesity and type II diabetes. In the present study, leptin cDNA was cloned from mouse fat cells by RT-PCR and prokaryotic expression of leptin was attempted in order ot prepare a leptin-specific antigen. Immunization of a rabbit with the leptin-specific antigen into a rabbit resulted in the generation of leptin-specific antiserum that could be useful in the detection of leption expressed in various tissues. The sequence of leptin cDNA prepared in the present study wa identical to the previously reported one. Transformation of E. coli(DH5a) cells with the leptin cDNA-inserted translation vector, pGEX-4T-3-leptin followed by treatment with IPTG (0.1mM) resulted in the expression of a large amount of GST-leptin fusion protein with a molecular weight of 44 KDa as an inclusion body. Denaturation of the insoluble fusion protein by 8M urea, 6M guanidium-HCI or 0.1% 2-mercaptoethanol followed by a slow oxidation could not solubilize the inclusion body. The cell extract was subjected to SDS-PAGE and GST-leptin protein electroeluted from the gel was then injected into a rabbit subcutaneously for the immunization. Anti-GST-leptin rabbit antiserum which had a cross reactivity to the GST-leptin protein was generated. Leptin protein expressed in mouse brain and fat tissues was detected by Western blot immunodetection system using the antiserum generated in the present study.

• 천문학회보
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• 제45권1호
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• pp.30.1-30.1
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• 2020

The ASKAP-EMU survey is a deep wide-field radio continuum survey designed to cover the entire southern sky and a significant fraction of the northern sky up to +30°. Here, we report a discovery of a radio relic in the merging cluster SPT-CL J2023-5535 at z=0.23 from the ASKAP-EMU pilot 300 square degree survey (800-1088 MHz). The deep high-resolution data reveal a ~2 Mpc-scale radio halo elongated in the east-west direction, coincident with the intracluster gas. The radio relic is located at the western edge of this radio halo stretched ~0.5 Mpc in the north-south orientation. The integrated spectral index of the radio relic within the narrow bandwidth is α1088MHz800MHz = -0.76 ± 0.06. Our weak-lensing analysis shows that the system is massive (M200 = 1.04 ± 0.36 × 1015M⊙) and composed of at least three subclusters. We suggest a scenario, wherein the radio features arise from the collision between the eastern and middle subclusters. Furthermore, the direct link between the local AGN and the relic along with the discontinuities in X-ray observation hint us that we are looking at the site of re-acceleration.

• 생명과학회지
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• 제11권4호
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• pp.346-353
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• 2001

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) a prototype of the highly toxid halogenated arylhydrocarbons, bioaccumulates in the food chain and induces a complex spectrum of pathological responses. However, its effect on the nerve system is relatively not well studied. In this study we evaluated TCDDs cytotoxicity on the cortical cell and investigated its effect on the expression 2,3-cyclic nucleotide 3-phosphodiesterase(CNPase), a marker for oilgodendrocytes, The survival rates of 4 DIV cortical cells, that are dissociated from E18 rat cortex and maintained in the presence of TCDD, were 88.8, 83.6, 78.5, and 78.6%(5,10, 20 and 50 nM, respectively) where the reduction in 20 and 50mM TCDD were statistically very significant(p<0.01). Imunocytochemistry of cultured cells revealed that the intensities of immunostaining with an anti-CNP1&2 antibody depended on the concentrations of the toxin. Immunoblot analysis also showed differential expression of CNP1 and CNP2 in the presence of TCDD; the CNP1 expression was dose-dependently decreased. Interestingly, the expression of CNP2 in the presence if TDCC; the CNP1 expression was dose-dependently decreased. Interestingly, the expression of CNP2 fluctuated with the TCDD concentration. These results indicated that CNP1 and 2 are differentially regulated by TCDD, implying the functions of oligodendrocytes are modulated by the toxin.

• 대한임상검사과학회지
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• 제49권4호
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• pp.390-394
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• 2017

비예기항체(unexpected antibody)는 ABO 혈액형 항체와는 달리 존재 여부를 미리 예측할 수 없는 항체로 주로 임신이나 수혈 등에 의해 다른 적혈구 항원에 노출됨으로써 발생하는 면역항체로서, 비예기항체는 해당 항원을 가진 수혈된 적혈구를 파괴하여 급성 및 지연성 용혈성부작용이나 신생아용혈성질환 등의 수혈부작용을 유발할 수 있다. 2014년 1월부터 2016년 12월까지 3년간 제주특별자치도 종합병원에 비예기항체 선별검사가 의뢰된 10,360명의 혈청 검체를 대상으로 하였으며, 의뢰된 비예기항체 선별결과 양성 결과를 보인 87 검체를 대상으로 조사하였다. 비예기항체가 선별되었던 87건 중 비예기항체 동정검사를 수탁검사기관으로 의뢰한 41 검체(0.40%) 대상으로 분석한 결과 비특이항체가 8건(19.51%), 자가항체가 3건(7.32%)이었다. 이들을 제외하고 항체가 동정된 것은 anti-E가 8건(19.51%), anti-E, anti-c 복합항체가 6건(14.63%), $anti-Le^a$, $anti-Le^b$ 복합항체가 3건(7.32%), $anti-Le^a$와 $anti-Le^b$가 각각 2건(4.88%)으로 조사되었다. 단일항체로는 anti-D, $anti-Di^a$, $anti-Fy^b$, $anti-Jk^a$, $anti-Jk^b$, anti-M, anti-P1이 각각 1건(2.44%)로 나타났으며 복합항체로는 anti-C+anti-D, anti-E+anti-c+$anti-Jk^b$가 각각 1건(2.44%)로 조사되었다. 단일항체가 동정된 검체는 19건(46.34%), 복합항체가 동정된 검체는 11건(26.83%)로 나타났다. 제주지역의 종합병원은 제주시와 서귀포시에 위치한 종합병원 7개 기관이 있으며, 모두 비예기항체 선별검사를 시행하고 있으며, 검사방법으로는 모든 검사실에서 Ortho BioVue system을 이용한 원주응집법으로 검사를 시행하고 있다. 하지만 비예기항체 동정검사는 외부수탁기관에 의뢰하고 있는 실정이다. 이번 연구는 최근 3년간 제주도내 종합병원 1개 기관에서의 동정된 비예기항체 빈도와 분포를 분석하였지만, 점차적으로 제주도내 다문화가정과 외국인 근로자가 증가 추세에 있어 향후 제주지역에 분포한 다수의 종합병원에서 동정되는 비예기항체의 빈도와 분포를 비교 분석한다면 의미가 있는 연구가 될 것이라고 사료된다.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.167-171
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• 2016

Background: TlBr is of considerable technological importance for radiation detection applications where detecting high-energy photons such as X-rays and ${\gamma}$-rays are of prime importance. However, there were few reports on investigating optical properties of TlBr itself for deeper understandings of this material and for making better radiation detection devices. Thus, in this paper, we report on the optical characterizations of TlBr single crystals. Spectroscopic ellipsometry (SE) and photoluminescence (PL) measurements at RT were performed for this work. Materials and Methods: A 2-inch TlBr single crystalline ingot was grown by using the vertical Bridgman furnace. SE measurements were performed at RT within the photon energy range from 1.1 to 6.5 eV. PL measurements were performed at RT by using a home-made PL system equipped with a 266 nm-laser and a spectrometer. Results and Discussion: Dielectric responses from SE analysis were shown to be slightly different among the different samples possibly due to the different structural/optical properties. Also from the PL measurements, it was observed that the peak intensities of the middle samples were significantly higher than those of the other two samples. With the given values for permittivity of free space (${\varepsilon}_0=8.854{\times}10^{-12}F{\cdot}m^{-1}$), thickness (d = 1 mm), and area ($A=10{\times}10mm^2$) of the TlBr sample, capacitances of TlBr were 6.9 pF (at $h{\nu}=3eV$) and 4.4 pF (at $h{\nu}=6eV$), respectively. Conclusion: SE and PL measurement and analysis were performed to characterize TlBr samples from the optical perspective. It was observed that dielectric responses of different TlBr samples were slightly different due to the different material properties. PL measurements showed that the middle sample exhibited much stronger PL emission peaks due to the better material quality. From the SE analysis, optical, dielectric constants were extracted, and calculated capacitances were in the few pF range.