• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.147-152
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• 1991

양단이 고정된 보가 변형할 때에는 중간 평면의 신장을 수반하게 된다. 운동 의 진폭이 증가함에 따라 이 신장이 보의 동적 응답에 미치는 영향은 심각 하게 된다. 이러한 현상은 응력과 변형도와의 관계가 선형적이라 하더라도 변형도와 변위와의 관계식은 비선형이 되며 결국은 보의 비선형 운동방정식 을 낳게된다. 보는 연속계이긴하지만 근사를 위하여 다자유도계로 간주할 수 있다. 비선형 다자유도계에 있어서는 선형화된 계의 고유진동수끼리 적절한 관계를 가질 때 내부공진이 발생할 수 있다. 양단이 고정된 곧은 보의 비선 형 동적응답이 그동안 많이 연구되어 오고 있으며, 집중질량을 가지고 직각 으로 굽은 보의 해석을 위하여 내부공진을 고려한 해석적 혹은 실험적 연구 가 이루어져 왔다. 그중에서도 Nayfeh등은 조화가진 하의 핀과 꺾쇠로 고정 된(hinged-clamped) 보의 정상상태응답을 해석하기 위해 두 모우드 사이의 내부공진을 고려하였다. 이 연구에서는 세 모우드 사이의 내부공진을 고려하 여 강제진행 중인 보의 비선형 해석을 다루고자 한다. 이 문제에 관심을 갖 게 된 동기는 "연속계의 비선형 해석에서 더 많은 모우드를 포함시키면 어 떤 결과를 낳게 될 것인가\ulcorner"라는 질문에서 생겨난 것이다. 갤러킨 법을 이용 하여 비선형 편미분 방정식과 경계 조건으로 표현되는 이 문제를 연립 비선 형 상미분 방정식으로 변환한다. 다중시간법(the method of multiple scales) 을 이용하여 이 상미분 방정식을 정상상태에서의 세 모우드의 진폭과 위상 에 대한 연립비선형 대수방정식으로 변환한다. 이 대수방정식을 수치적으로 풀어서 정상상태 응답을 구하고 Nayfeh등의 결과와 비교한다. 결과와 비교한다. studies, the origin of ${\alpha}$$_1$peak was attributed to the detrapping process form trap with 2.88[eV] deep of injected space charge from the chathode in the crystaline regions. The origin of ${\alpha}$$_2$ peak was regarded as the detrapping process of ions trapped with 0.9[eV] deep originated from impurity-ion remained in the specimen during production process of the material, in the crystalline regions. The origin of ${\beta}$ peak was concluded to be due to the depolarization process of "C=0"dipole with the activation energy of 0.75[eV] in the amorphous regions. The origin of ${\gamma}$ peak was responsible to the process combined with the depolarization of "CH$_3$", chain segment, with the activation energy of carriers from the shallow trap with 0.4[eV], in he amorp

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.1943-1948
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• 2010

Two kind of $\beta$-SiC powders of different particle sizes (${\sim}1.7\;{\mu}m$ and ${\sim}30\;nm$), containing 7 wt% $Y_2O_3$, 2 wt% $Al_2O_3$ and 1 wt% MgO as sintering additives, were prepared by hot pressing at $1800^{\circ}C$ for 1 h under applied pressures, and then were hot-forged at $1950^{\circ}C$ for 6 h under 40 MPa in argon. All the hot-pressed specimens consisted of equiaxed grains and were developed grain growth after hot-forging. The smaller starting powder was developed the finer microstructure. The microstructures on the surfaces parallel and perpendicular to the pressing direction of the hot-forged SiC were similar to each other, and no texture development was observed because of the lack of massive $\beta$ to $\sigma$ phase transformation of SiC. The fracture toughness (${\sim}3.9\;MPa{\cdot}m^{1/2}$), hardness (~ 25.2 GPa) and flexural strength (480 MPa) of hot-forged SiC using larger starting powder were higher than those of the other.

• Korean Journal of Biological Psychiatry
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• v.22 no.4
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• pp.205-215
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• 2015

Objectives Sex hormones exposure during the prenatal period has an effect on cerebral lateralization. Male brains are thought to be more lateralized than female brains. Bipolar disorder was known to show abnormalities in cerebral laterality whose characteristics could be estimated by electroencephalography (EEG) coherences. We studied sex-related differences of EEG coherences between healthy controls and patients with bipolar disorder to examine the sex effects in the genesis of bipolar disorder. Methods Participants were 25 patients with bipolar disorder (11 male, 14 female) and 46 healthy controls (23 male, 23 female). EEG was recorded in the eyes closed resting state. To examine dominant EEG coherence associated with sex differences in both groups within five frequency bands (delta, theta, alpha, beta, and gamma) across several brain regions, statistical analyses were performed using analysis of covariance. Results Though statistically meaningful results were not found, some remarkable findings were noted. Healthy control females showed more increased interhemispheric coherences than control males in gamma frequency band. There were no differences in the intrahemispheric coherences between the healthy control males and females. In patients with bipolar disorder, female dominant pattern in interhemispheric coherences was attenuated compared with healthy control. Conclusions Sex differences of EEG coherences, which could be a marker for cerebral laterality, were attenuated in patients with bipolar disorder compared with healthy controls. These results imply that abnormal sex hormone exposure during early development might play some role in the pathogenesis of bipolar disorder.

• Journal of Life Science
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• v.8 no.5
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• pp.497-503
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• 1998

Cyclodextrinase from B. stearothemophilus KJ16 that can produce both cyclodextrin(CD) glucanotransferase and cyclodextrinase was purified 87.6-fold with 7% yield by ammonium sulfate precipitation, DEAE-cellulose chromatog-raphy, Sephadex G-100 chromatography, and FPLC. The molecular weight of the purified enzyme was about 68,000 dalton by SDS-PAGE. The optimal pH and temperature were 6.0 and 55$^{\circ}C$, respectively. The enzyme was stable at 5$0^{\circ}C$ for 2 hr in the pH range of 5.5 and 8.5. The enzyme activity was inhibited strongly by mercaptoethanol, di-thiothreitol, p-chloromercuribenzoate, N-bromosuccinimide, $Cu^{+2}$and $Hg^{+2}$. The purified enzyme hydrolyzed CDs with$\gamma$-CD>$\beta$-CD>$\alpha$-CD. The enzyme also hydrolyzed linear maltodextrins and polysaccharides, but the rates of hyd-rolysis for such substrates were slow as compared to that for $\gamma$-CD. The final degradation products with all substrates were maltose and glucose. Maltose was not further hydrolyzed.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.57-61
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• 2016

Thick film sealing glass paste is required for cell packaging of NaS based battery for energy storage system, to join the beta-alumina electrolyte tube and the alpha-alumina battery cell cap components. This paper presents the effect of the particle sizes of seal glass powder and the sealing temperatures on the microstructure of the glass sealants was investigated. It was found that the larger in the particle size of seal glass powder, the smaller the pore volume and the number of pores in a unit area. Also, the number of pores decreased with increasing the sealing temperatures while the pore size was increased. This result enables the control of porosity, pore distribution and number of pores in a microstructure of glass sealing component by proper selection of glass powders particle size and sealing temperature.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.347-351
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• 2020

A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.107-107
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• 2002

ADAM은 metalloprotease/disintegrin domain을 가진 transmembrane glycoprotein 으로서 지금까지 30개 이상의 ADAM 및 10개 이상의 ADAMTS 단백질이 알려져 있다. 이들의 기능은 포유동물의 수정시 sperm-egg binding과 fusion, myoblast fusion, integrin과의 결합 등에 직접 관여하거나, TNF-alpha 등의 생체 신호전달물질이 세포로부터 분비될 때에 이들의 구조를 변화시켜 활성화시키는 효소작용, 그리고 dendritic cell differentiation 등에 관여하는 것으로 알려져있다. 그러나 자궁내막 조직에서의 유전자 및 단백질 발현 여부에 관해서는 거의 보고되어 있지 않고 있다. 먼저 RT-PCR 방법을 이용하여 자궁에서 mRNA의 양을 $\beta$-actin의 양에 대하여 상대적으로 측정한 결과, 임신 1일부터 5일까지는 ADAM-9, 10, 17, TS1의 mRNA 경우 거의 비슷하게 발현되었으며 ADAM-8과 15는 3일째, ADAM-12는 2일째와 4일째에 현저하게 증가하였다 임신 6일부터 8일까지의 자궁조직을 각각 embryo가 착상된 곳과 그렇지 않은 곳으로 나누어 조사한 결과 상대적으로 착상이 된 곳에서 mRNA가 많이 발현 되었으며 특히 ADAM-8, 12, 15의 mRNA의 경우 현저한 차이를 보였다. Immunoblotting 방법을 이용하여 임신 1일부터 5일까지의 단백질의 발현 양상을 조사한 결과 임신 ADAM-8은 3일 이후 감소되는 양상을 보였으며 ADAM-9, 15, TS1은 5일째에 증가하는 양상을 보였다. ADAM-10은 2일째 감소하다가 다시 증가하고 ADAM-12, 17은 3, 4일째 증가하다가 5일째 감소하는 상을 보였다. 한편 임신 6일부터 8일까지는 embryo가 착상된 곳이 그렇지 않은 곳보다 조사된 모든 ADAMs 단백질이 상대적으로 많이 발현되는 양상을 보였다. 이러한 결과로 미루어 ADAMs은 임신 초기 착상과정과 임신 단계에 따른 자궁의 조직 재구성에 중요한 역할을 할 것으로 생각된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.126-130
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• 2016

Ti alloys have been used for orthopedic devices, automobile and aircraft because it has several beneficial properties such as a low density, a low modulus of elasticity, excellent high-temperature strength, excellent corrosion resistance and biocompatibility. In this study, Ti-64 composition (6 wt% Al, 4 wt% V) is investigated as a representative Ti-alloy system on the crystallographic characteristics and microstructure. We investigated crystal structure of the Ti-64 sample by XRD, and analyzed microstructure by compositional differences measured using FE-SEM and EDX.

• Korean Journal of Biological Psychiatry
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• v.21 no.4
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• pp.151-160
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• 2014

Objectives Prenatal testosterone is known to influence both cerebral laterality and 2nd to 4th digit ratio (2D : 4D). Epigenetic changes are thought to play some role in it. We studied sex-related differences between 2D : 4D and cerebral laterality in patients with schizophrenia and controls to examine the effects of prenatal testosterone in the development of schizophrenia. Methods Forty one men (18 schizophrenic patients and 23 controls) and 40 women (17 schizophrenic patients and 23 controls) were recruited from one psychiatric hospital in Korea. The 2D : 4D and electroencephalographic (EEG) coherence in 19 channels (66 pairs of interhemispheric coherence and 54 pairs of intrahemispheric coherence) were measured. The sex-related statistical analyses between 2D : 4D and EEG coherence in controls and patients with schizophrenia were performed using multiple regression. Results In male patients, the relationship between 2D : 4D and right intrahemispheric EEG coherence showed mainly positive correlation in delta and theta frequency bands, while it showed negative correlation in male controls. In female patients, the relationship between 2D : 4D and interhemispheric EEG coherence showed stronger positive correlation in alpha and beta frequency bands, while it showed weaker positive correlation in female controls. Conclusions Low prenatal testosterone may play certain roles in altered correlation between 2D : 4D and cerebral laterality in schizophrenia and the development of schizophrenia by epigenetic mechanism.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.4
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• pp.278-286
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• 2009

In this study, four natural Mn oxides ($NMO_1-NMO_4$) was characterized using x-ray diffraction, scanning electron microscopy, and their removal efficiency for 1-naphthol (1-NP) in aqueous phase, using batch reactor, was investigated. The results were compared with one another and a synthetic manganese oxide, birnessite. The NMOs have a various Mn minerals including pyrolusite (${\beta}-MnO_2$), cryptomeltane (${\alpha}-MnO_2$) as well as birnessite (${\delta}-MnO_2$) depending on their sources, which results in different removal efficiencies (removals, kinetics) and reaction types (sorption or oxidative-transformation). The comparative study showed that $NMO_1$ (electrolytic Mn oxide) have a higher removal efficiency for 1-NP via oxidative-transformation compared to birnessite. The 1-NP removals by NMOs were followed by pseudo-first order reaction, and the surface area-normalized specific rate constants ($K_{surf},\;L/m^2$ min) determined were in order of $NMO_1(3.31{\times}10^{-3})$>${\delta}-MnO_2(1.48{\times}10^{-3}){\fallingdotseq}NMO_3(1.46{\times}10^{-3})$>$NMO_2(0.83{\times}10^{-3})$>$NMO_4(0.67{\times}10^{-3})$. From the solvent extraction experiments with the Mn oxide precipitates after reaction, it was observed that the oxidative-transformation rates of 1-NP were in order of $NMO_1{\fallingdotseq}{\delta}-MnO_2$>$NMO_3$>$NMO_4{\gg}NMO_2$ and the analysis of HPLC chromatogram and UV-Vis. absorption ratios ($A_{2/4}$, $A_{2/6}$) on the supernatant confirmed that the reaction products were oligomers formed by oxidative-coupling reaction. Results from this study proved that natural Mn oxide (except $NMO_2$) used in this experiment can be effectively applied for the removal of naphthols in aqueous phase, and the removal efficiencies are depending on the surface characters of the Mn oxides.