• 치과방사선
• /
• 제28권1호
• /
• pp.87-109
• /
• 1998

The present study was designed to elucidate the effects of the Co-60 γ irradiation and/or calcium­deficient diet on the dentin and cementum formation of rat molar. The pregnant three-week old Sprague­Dawley rats were used for the study. The experimental group was divided into two groups, irradiation/normal diet group and irradiation/calcium-deficient diet group. The control group was non­irradiation/normal diet group. The abdomen of the rats at the 19th day of pregnancy were irradiated with single absorbed dose of 350cGy. The rat pups were sacrificed on the 14th day after delivery and the maxillae including molar tooth germ were taken. The specimens including the 1st molar tooth germ were prepared to make tissue sections for light and transmission electron microscopy. Some of tissue sections for light microscopy were stained immunohistochemically with anti-fibronectin antibody. The results were as follows; 1. The Hertwig's epithelial root sheath cells, which are related to the differentiation of the tooth-forming cells, showed irregular cellular arrangement, decrease of intercellular junctional complex, and decreased immunoreactivity to the fibronectin after irradiation. These were more severe in the irradiation/calcium-deficient diet group. 2. The cementoblasts at the cementum-forming area showed chromatin clumpings after irradiation. The immu noreactivity to the fibronectin was weaken after irradiation, especially irradiation/calcium-deficient diet group. 3. The odontoblasts at the dentin-forming area showed increase of lysosomes in the cytoplasm and destruction of intercellular junctional complex. The irradiation/calcium-deficient diet group showed decrease of number and density of the electron dense particles and a large number of vacuoles scattered in the dentin matrix. The immunoreactivity was weaken.

• 대한기계학회논문집
• /
• 제13권3호
• /
• pp.461-471
• /
• 1989

본 연구에서는 혼합 모우드 균열문제의 연구를 위하여 .KAPPA.$_{II}$ /.KAPPA.S1I\ulcorner조절이 간편하고, 균열진전경로가 하중방향에 따른 균일전면의 자유표면의 영향을 균일하게 한 시험편(이하 RCM 또는 round compact mixed-mode 시험편이라 한다)을 고안하여 균열길이 및 하중작용 방향에 따른 .KAPPA.$_{I}$ 및 .KAPPA.S1II를 수치해석한 다음 일반화 하였다. 또 고강도와 용접성이 요구되는 항공기부품, 압력용기, 지상운송차량 등에 사용되고 있는 5083-H115 알루미늄 합금에 대해 혼합 모우드 균열진전 방향 및 피로균열 진전특성을 분석하고자 한다.다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.45-45
• /
• 2007

Capacitors among the embedded passive components are most widely studied because they are the major components in terms of size and number and hard to embed compared with resistors and inductors due to the more complicated structure. To fabricate a capacitor-embedded PCB for in-line process, it is essential to adopt a low temperature process (<$200^{\circ}C$). However, high dielectric materials such as ferroelectrics show a low permittivity and a high dielectric loss when they are processed at low temperatures. To solve these contradicting problems, we studied BMN materials as a candidate for dielectric capacitors. processed at PCB-compatible temperatures. The morphologies of BMN thin films were investigated by AFM and SEM equipment. The electric properties (C-F, I-V) of Pt/BMN/Cu/polymer were evaluated using an impedance analysis (HP 4194A) and semiconductor parameter analyzer (HP4156A). $Bi_2Mg_{2/3}Nb_{4/3}O_7$(BMN) thin films deposited on copper clad laminate substrates by sputtering system as a function of Ar/$O_2$ flow rate at room temperature showed smooth surface morphologies having root mean square roughness of approximately 5.0 nm. 200-nm-thick films deposited at RT exhibit a dielectric constant of 40, a capacitance density of approximately $150\;nF/cm^2$, and breakdown voltage above 6 V. The crystallinity of the BMN thin films was studied by TEM and XRD. BMN thin film capacitors are expected to be promising candidates as embedded capacitors for printed circuit board (PCB).

• 한국토양비료학회지
• /
• 제47권4호
• /
• pp.242-248
• /
• 2014

We have five soil series of pan soils in South Korea out of 391 series: Gangreung, Bugog, Yeongog, Jangweon, and Pogog. Productivity decreases in pan soils as pan horizons impede percolation and capillary rise of water and interrupt root extension. This study was performed to investigate pedogenic processes of pan soils mainly located in footslope and river terrace by analyzing physicochemical properties and soil micro-morphology. Korean pan soils belong to Alfisols, Ultisols, or Inceptisols and have udic or aquic soil moisture regime, mesic temperature regime, and mixed mineral substances. Texture of pan horizons selected for the present study was mainly silty clay loam with clay contents ranging from 26.3 to 45.3%. Bulk density of the pan horizons ranged from 1.4 to $2.1Mg\;m^{-3}$ and their soil structure were subangular or angular structure. In terms of micro-morphological structure, Bt horizon of Gangreung series was formed as platy and striated b-fabric structure possibly affected by uplift of coastal terrace following clay sedimentation by flood. Jangweon series showed micro-morphology of massive structure and crystallic b-fabric as macropores between coarse debris established by debris fall in slope were filled with silt-sized particles. The Bt horizons having massive structure and striated b-fabric in Yeongog, Pogog, and Bugog series implies that those horizons experienced horizontal mass flow after clay accumulation.

• Food Science and Biotechnology
• /
• 제17권6호
• /
• pp.1228-1234
• /
• 2008

Having idea to develop more effective anti-diabetic agent from ginseng root, we comprehensively assessed the anti-diabetic activity and mechanisms of ginsam in C57BL/KsJ db/db mice. The db/db mice were divided into 4 groups; diabetic control (DC), ginsam at a dose of 300 or 500 mg/kg (GS300 or GS500) and metformin at a dose of 300 mg/kg (MT300). Ginsam was orally administered for 8 weeks. GS500 reduced the blood glucose concentration and significantly decreased an insulin resistance index. In addition, GS500 reduced the plasma non-esterified fatty acid, triglyceride, and increased high density lipoprotein-cholesterol as well as decreased the hepatic cholesterol and triglyceride. More interestingly, ginsam increased the plasma adiponectin level by 17% compared to diabetic control group. Microarray, quantitative-polymerase chain reaction and enzyme activity results showed that gene and protein expressions associated with glycolysis, gluconeogenesis, and fatty acid oxidation were changed to the way of reducing hepatic glucose production, insulin resistance and enhancing fatty acid $\beta$-oxidation. Ginsam also increased the phosphorylation of AMP-activated protein kinase and glucose transporter expressions in the liver and skeletal muscle, respectively. These changes in gene expression were considered to be the mechanism by which the ginsam exerted the anti-diabetic and anti-dyslipidemic activities in C57BL/KsJ db/db mice.

• 한국초지조사료학회지
• /
• 제37권3호
• /
• pp.242-247
• /
• 2017

Humic acid (HA) is a complex organic matter found in the environments, especially in grassland soils with a high density. The bioactivity of HA to promote plant growth depends largely on its extraction sources. The quality-control of HA and the quality improvements via an artificial synthesis are thus challenging. We recently reported that a polymeric product from fungal laccase-mediated oxidation of catechol and vanillic acid (CAVA) displays a HA-like activity to enhance seed germination and salt stress tolerance in a model plant, Arabidopsis. Here, we examined whether HA or CAVA enhances the growth of Italian ryegrass seedling. Height and fresh weight of the plant with foliar application of HA or CAVA were bigger than those with only water. Interestingly, enhanced root developments were also observed in spite of the foliar treatments of HA or CAVA. Finally, we proved that HA or CAVA promotes the regrowth of Italian ryegrass after cutting. Collectively, CAVA acts as a HA mimic in Italian ryegrass cultivation, and both as a biostimulant enhanced the early growth and regrowth after cutting of Italian ryegrass, which could improve the productivity of forage crops.

• 한국자기공명학회논문지
• /
• 제20권3호
• /
• pp.95-101
• /
• 2016

Apolipoprotein B-100 (Apo-B100) is a major component of low density lipoprotein (LDL). Apo B-100 protein has 4,536 amino acid sequence and these amino acids are classified into peptide groups A to G with subsequent 20 amino acids (P1-P302). The peptide groups were act as immunoglobulin (Ig) antigens which oxidized via malondialdehyde (MDA). The mimetic peptide P1 (EEEMLENVSLVCPKDAT RFK) out of D-group peptides carrying the highest value of IgG antigens were selected for structural studies that may provide antigen specificity. Circular Dichroism (CD) spectra were measured for peptide secondary structure in the range of 190-250 nm. Experimental results show that P1 exhibit partial of ${\beta}-sheet$ and random coil structure. Homonuclear (COSY, TOCSY, NOESY) 2D-NMR experiments were carried out for NMR signal assignments and structure determination for P1. On the basis of these completely assigned NMR spectra and distance data, distance geometry (DG) and Molecular dynamics (MD) were carried out to determine the structures of P1. The proposed structure was selected by comparisons between experimental NOE spectra and back calculated 2D NOE results from determined structure showing acceptable agreement. The total Root-Mean-Square-Deviation (RMSD) value of P1 obtained upon superposition of all atoms was in the range $0.33{\AA}$. The solution state P1 has mixed structure of ${\beta}-sheet$ (Glu[1] to Cys[12]) and random coil (Pro[13] to Lys[20]). These NMR results are well consistent with secondary structure from experimental results of circular dichroism. Structural studies based on NMR may contribute to the studies of atherosclerosis and observed conformational characteristics of apo B-100 in LDL using monoclonal antibodies.

• 한국항행학회논문지
• /
• 제17권6호
• /
• pp.693-699
• /
• 2013

본 논문에서는 ITU-R M.1842-1 표준 권고안 Annex1에 따르는 ${\pi}/4$-DQPSK 모뎀에 대해 분석하고 시뮬레이션을 수행하였다. 우선 VHF 대역의 해상 이동통신에 대한 표준 및 기술동향을 소개하였다. Annex1에 제시된 ${\pi}/4$-DQPSK 모뎀은 25KHz의 대역폭에서 28.8Kbps 비트전송률을 제공하도록 제시되어 있다. 송수신기에서 RRC필터를 채용하는 ${\pi}/4$-DQPSK 모뎀의 시뮬레이션 프로세스에 대해 설명하고, 다양한 시뮬레이션 결과(시간영영 신호파형, 성좌도, 롤오프 팩터에 따른 전력스펙트럼밀도, Eye 다이어그램)들과 모뎀의 BER 성능을 제시하였다. 시뮬레이션 결과로부터, RRC 필터의 롤오프 팩터에 의해서 SNR에 따른 BER 성능에 미치는 영향이 다름을 확인하였고, 설계한 시뮬레이션 모델이 ITU-R M.1842-1 권고안에 제시된 스펙트럼 마스크 요구사항을 만족함을 알 수 있었다.

• Restorative Dentistry and Endodontics
• /
• 제25권2호
• /
• pp.180-192
• /
• 2000

One bottle system was recently developed in order to simplify the clinical skills and save chair time after continuous improvements on dentin bonding agents. There has been many studies to measure the bond strength of one bottle systems but no actual work has been done on micromorphologic study of resin-dentin interdiffusion zone after one bottle system application. To evaluate the bonding patterns of various commercially available one bottle systems to dentin, observation of resin-dentin interdiffusion zone under TEM was performed. Caries-free human third molars within one month of extractions were chosen for the experiments. The molars were sectioned 1mm above the cementoenamel junction and got rid of the root portions. Crown portions of the teeth were sectioned parallel to occlusal surface so that dentin discs of 1mm in thickness were remained. 7 one bottle systems and 1 two bottle system were applied according to manufacturer's instructions and followings were the results. 1. In every experimental groups, cross bandings of collagen fiber were distinguishable and tight bon dings between the bonding agents and dentin were observed. 2. Hybrid layer was clearly observed in ONE-STEP$^{(R)}$, Prime & Bond$^{(R)}$ 2.1, Syntac$^{(R)}$ SC, MAC-BOND II groups but it was not clear in Single Bond, D-Liner Dual PLUS, ONE COAT BOND groups. 3. Electron-density of hybrid layer was uniform in pattern in MAC-BOND II, Prime & Bond$^{(R)}$ 2.1 groups but not so uniform in ONE-STEP$^{(R)}$ group. 4. Electron-dense amorphous phase in most superior layer of the resin-dentin interdiffusion zone was characteristically observed in Single Bond, Syntac$^{(R)}$ SC, ONE COAT BOND groups. It can be concluded that bondings between the dentin bonding agents and dentin can be various in pattern according to their chemical compositions and the condition during applications.

• 대한화장품학회지
• /
• 제36권1호
• /
• pp.33-39
• /
• 2010

최근 합성 염모제의 부작용들 때문에 인체에 무해한 천연재료를 이용한 염색에 대한 관심이 고조되어 있다. 본 연구에서는 농산 폐기물인 칡뿌리 추출물을 이용해 탈색 모발에 천연 염색을 함으로써 염색에 적절한 염색 시간, 염색시 온도와 매염과 매염제 처리 농도 변화 등에 따른 모발의 염색 정도를 색차계를 통해 조사하였다. 합성 염모제가 가진 화학 물질로 인한 모발 손상에 비해 칡뿌리 추출물을 이용한 모발 염색은 손상도를 낮춰주고 큐티클을 부드럽게 유지시키는 결과를 가져왔다. 칡 추출물만으로 염색한 모발이 가장 어두워짐을 관찰함으로써, 매염제는 염색의 보조 역할을 하는 성분임을 알 수 있었다. 본 연구의 결과를 종합하여 볼 때 칡뿌리 추출물은 합성 염모제에 비해 모발 손상도가 적으며 칡뿌리 추출물을 천연 모발 염모제의 주원료로써 활용가치가 있음을 제안하는 바이다.